A SOAP-based Model for secure messaging in a global context
- Authors: Van Eeden, Johannes Jurie
- Date: 2005
- Subjects: Telecommunication systems -- Security measures
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9777 , http://hdl.handle.net/10948/817 , Telecommunication systems -- Security measures
- Description: For integration between application-systems in a global context, interoperability needs to be established on a global level; global interoperability, in turn, is based on a global common application-interface. This is achieved through resolving differences in, inter alia, protocol profiles, among participants in the global network. ebXML is used as the point of departure. A messaging framework, which is based on existing Web technology and standards, is proposed. Certain security and Web service standards are examined to determine specific parameters for an interoperable secure messaging environment. A security based framework comprising a predefined message format and architecture is investigated for a secure interoperable global electronic marketspace.
- Full Text:
- Date Issued: 2005
- Authors: Van Eeden, Johannes Jurie
- Date: 2005
- Subjects: Telecommunication systems -- Security measures
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9777 , http://hdl.handle.net/10948/817 , Telecommunication systems -- Security measures
- Description: For integration between application-systems in a global context, interoperability needs to be established on a global level; global interoperability, in turn, is based on a global common application-interface. This is achieved through resolving differences in, inter alia, protocol profiles, among participants in the global network. ebXML is used as the point of departure. A messaging framework, which is based on existing Web technology and standards, is proposed. Certain security and Web service standards are examined to determine specific parameters for an interoperable secure messaging environment. A security based framework comprising a predefined message format and architecture is investigated for a secure interoperable global electronic marketspace.
- Full Text:
- Date Issued: 2005
Study of the skincalm filling process at Aspen Pharmacare applying some six sigma principles
- Authors: Marx, Johannes
- Date: 2005
- Subjects: Ointments -- Packaging , Six sigma (Quality control standard)
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10369 , http://hdl.handle.net/10948/184 , Ointments -- Packaging , Six sigma (Quality control standard)
- Description: Aspen Pharmacare is listed on the Johannesburg Securities Exchange South Africa (JSE) and is Africa’s largest pharmaceutical manufacturer. The company is a major supplier of branded pharmaceutical and healthcare products to the local and selected international markets. For decades, Aspen has manufactured a basket of affordable, quality, and effective products for the ethical, generic over-the-counter (OTC) and personal care markets. Aspen is also the leading supplier of generic medicines to the public sector, providing comprehensive coverage of the products on the Essential Drug List. Aspen continues to deliver on its commitment toward playing a role in social responsibility diseases such as HIV/AIDS, tuberculosis and malaria. In August 2003 Aspen developed Africa’s first generic anti-retroviral drug, namely Aspen-Stavudine. Aspen’s manufacturing facilities are based in Port Elizabeth (PE) and East London. Aspen has recently completed an Oral Solid Dosage (OSD) manufacturing facility worth approximately R150 million in PE. The Group manufactures approximately 20 tons of product daily and in excess of 400 tons of solid dosage pharmaceuticals, which equates to more than 2 billion tablets. In addition, more than 3 million litres of liquid pharmaceuticals and over 200 tons of pharmaceutical creams and ointments are produced per year [1]. Aspen excels at delivering quality products and services, exceeding customer expectations, complying with international standards in an environment that cultivates technical expertise and innovation. Following this philosophy through to the shop floor areas mean that there are always initiatives in continuous production improvement. One of these improvement projects introduced is called Six Sigma. 8 Ten members of the staff, selected from different expertise fields in the company were trained in Six Sigma. Knowledge gained from the two week training course were applied to different areas in the factory using Six Sigma principles. This dissertation focuses on the study undertaken in one of production areas, namely the filling process of the ointments and creams at the Aspen Port Elizabeth facility.
- Full Text:
- Date Issued: 2005
- Authors: Marx, Johannes
- Date: 2005
- Subjects: Ointments -- Packaging , Six sigma (Quality control standard)
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10369 , http://hdl.handle.net/10948/184 , Ointments -- Packaging , Six sigma (Quality control standard)
- Description: Aspen Pharmacare is listed on the Johannesburg Securities Exchange South Africa (JSE) and is Africa’s largest pharmaceutical manufacturer. The company is a major supplier of branded pharmaceutical and healthcare products to the local and selected international markets. For decades, Aspen has manufactured a basket of affordable, quality, and effective products for the ethical, generic over-the-counter (OTC) and personal care markets. Aspen is also the leading supplier of generic medicines to the public sector, providing comprehensive coverage of the products on the Essential Drug List. Aspen continues to deliver on its commitment toward playing a role in social responsibility diseases such as HIV/AIDS, tuberculosis and malaria. In August 2003 Aspen developed Africa’s first generic anti-retroviral drug, namely Aspen-Stavudine. Aspen’s manufacturing facilities are based in Port Elizabeth (PE) and East London. Aspen has recently completed an Oral Solid Dosage (OSD) manufacturing facility worth approximately R150 million in PE. The Group manufactures approximately 20 tons of product daily and in excess of 400 tons of solid dosage pharmaceuticals, which equates to more than 2 billion tablets. In addition, more than 3 million litres of liquid pharmaceuticals and over 200 tons of pharmaceutical creams and ointments are produced per year [1]. Aspen excels at delivering quality products and services, exceeding customer expectations, complying with international standards in an environment that cultivates technical expertise and innovation. Following this philosophy through to the shop floor areas mean that there are always initiatives in continuous production improvement. One of these improvement projects introduced is called Six Sigma. 8 Ten members of the staff, selected from different expertise fields in the company were trained in Six Sigma. Knowledge gained from the two week training course were applied to different areas in the factory using Six Sigma principles. This dissertation focuses on the study undertaken in one of production areas, namely the filling process of the ointments and creams at the Aspen Port Elizabeth facility.
- Full Text:
- Date Issued: 2005
Optimising the material distribution process for the southern region of Telkom SA
- Authors: Naicker, Kosalin Ganasen
- Date: 2005
- Subjects: Business logistics -- South Africa , Telecommunication -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8547 , http://hdl.handle.net/10948/407 , Business logistics -- South Africa , Telecommunication -- South Africa
- Description: Most government owned telecommunication operators across the world have to deal with a number of regulatory, technology and service challenges, as the industry is liberalised in co-ordinance with worldwide trends. Telkom SA will be facing a number of strategic challenges that will test its ability to survive as a telecommunications company over the next number of years. To remain competitive, Telkom must develop strategies to assure survival in a competitive environment. To assure the long-term survival of Telkom SA when moving into a competitive environment, the organisation must build a sustainable competitive advantage. In the face of increasingly fierce competition, the adoption of collaborative alliances between firms is becoming more and more common and the adoption of a world-class supply chain will be an ideal scenario for Telkom SA. A worldclass supply chain goes beyond the scope of the internal operations of an organisation, therefore the material distribution process was chosen for this study, which involved the internal operations in the organisation. The study included the availability of material up to the transportation of the material to the staging areas. The aim of this research was to identify the inefficiencies of the material distribution process of the Southern Region of Telkom SA to become worldclass. A quantitative technique was used to identify the inefficiencies. It was found that the availability and transportation of material were the inefficient categories, preventing the customer to receive the product or service on time. Communication, inaccurate forecasting and inefficient transportation of material were some of the reasons for not delivering material on time. Some of the recommendations included developing a model that could overcome the current inefficiencies in transportation, improving the communication channels, training and the development of employees at all levels.
- Full Text:
- Date Issued: 2005
- Authors: Naicker, Kosalin Ganasen
- Date: 2005
- Subjects: Business logistics -- South Africa , Telecommunication -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8547 , http://hdl.handle.net/10948/407 , Business logistics -- South Africa , Telecommunication -- South Africa
- Description: Most government owned telecommunication operators across the world have to deal with a number of regulatory, technology and service challenges, as the industry is liberalised in co-ordinance with worldwide trends. Telkom SA will be facing a number of strategic challenges that will test its ability to survive as a telecommunications company over the next number of years. To remain competitive, Telkom must develop strategies to assure survival in a competitive environment. To assure the long-term survival of Telkom SA when moving into a competitive environment, the organisation must build a sustainable competitive advantage. In the face of increasingly fierce competition, the adoption of collaborative alliances between firms is becoming more and more common and the adoption of a world-class supply chain will be an ideal scenario for Telkom SA. A worldclass supply chain goes beyond the scope of the internal operations of an organisation, therefore the material distribution process was chosen for this study, which involved the internal operations in the organisation. The study included the availability of material up to the transportation of the material to the staging areas. The aim of this research was to identify the inefficiencies of the material distribution process of the Southern Region of Telkom SA to become worldclass. A quantitative technique was used to identify the inefficiencies. It was found that the availability and transportation of material were the inefficient categories, preventing the customer to receive the product or service on time. Communication, inaccurate forecasting and inefficient transportation of material were some of the reasons for not delivering material on time. Some of the recommendations included developing a model that could overcome the current inefficiencies in transportation, improving the communication channels, training and the development of employees at all levels.
- Full Text:
- Date Issued: 2005
Critical analysis of a performance management system used by a tertiary education institution in the Eastern Cape
- Mkovane, Zenephone Bhekuyise
- Authors: Mkovane, Zenephone Bhekuyise
- Date: 2005
- Subjects: Performance -- Management -- Evaluation , Performance -- Measurement -- Evaluation , Universities and colleges -- Employees -- Rating of -- South Africa -- Eastern Cape , Border Technikon -- Employees -- Rating of
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8567 , http://hdl.handle.net/10948/412 , Performance -- Management -- Evaluation , Performance -- Measurement -- Evaluation , Universities and colleges -- Employees -- Rating of -- South Africa -- Eastern Cape , Border Technikon -- Employees -- Rating of
- Description: As argued by authors like Franzen on whose work the greater part of the introduction, the main problem and sub-problem has been based, the objective of this study was to establish the extent to which the performance evaluation system currently in use at the subject Institution conforms to the benchmark performance management systems as espoused in literature. Further, the objective was to establish the differences and commonalities between the performance management systems practiced in the corporate sector and current practice at the subject Institution. Best practice was thus lifted to form part of the recommendation of this study. A questionaire was designed based on the guidelines in the literature study in order to determine how the subject Institution conducts its performance appraisal and how this relates to the four general purposes of performance management mentioned in the study. The respondents' opinion obtained from the questionaire were compared with the guidelines in literature and clustered around the four identifiable general purposes of performance management. The study concludes with a statement of current practice at the subject Institution, and outlines the extent of conformance to benchmark practice on performance management systems. Recommendations are made based on best practice and direction is given to future research into contemporary practices with the express aim of enhancing quality in higher education applying the quality-related procedures of industry and commerce, where quality is crucial to success (Winch, 1996: 9-13). The current performance management system at the subject Institution proves to be largely conforming to the benchmark. However it should require comments made by the respondents that pertain to improvement.
- Full Text: false
- Date Issued: 2005
- Authors: Mkovane, Zenephone Bhekuyise
- Date: 2005
- Subjects: Performance -- Management -- Evaluation , Performance -- Measurement -- Evaluation , Universities and colleges -- Employees -- Rating of -- South Africa -- Eastern Cape , Border Technikon -- Employees -- Rating of
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8567 , http://hdl.handle.net/10948/412 , Performance -- Management -- Evaluation , Performance -- Measurement -- Evaluation , Universities and colleges -- Employees -- Rating of -- South Africa -- Eastern Cape , Border Technikon -- Employees -- Rating of
- Description: As argued by authors like Franzen on whose work the greater part of the introduction, the main problem and sub-problem has been based, the objective of this study was to establish the extent to which the performance evaluation system currently in use at the subject Institution conforms to the benchmark performance management systems as espoused in literature. Further, the objective was to establish the differences and commonalities between the performance management systems practiced in the corporate sector and current practice at the subject Institution. Best practice was thus lifted to form part of the recommendation of this study. A questionaire was designed based on the guidelines in the literature study in order to determine how the subject Institution conducts its performance appraisal and how this relates to the four general purposes of performance management mentioned in the study. The respondents' opinion obtained from the questionaire were compared with the guidelines in literature and clustered around the four identifiable general purposes of performance management. The study concludes with a statement of current practice at the subject Institution, and outlines the extent of conformance to benchmark practice on performance management systems. Recommendations are made based on best practice and direction is given to future research into contemporary practices with the express aim of enhancing quality in higher education applying the quality-related procedures of industry and commerce, where quality is crucial to success (Winch, 1996: 9-13). The current performance management system at the subject Institution proves to be largely conforming to the benchmark. However it should require comments made by the respondents that pertain to improvement.
- Full Text: false
- Date Issued: 2005
A study of the use of value based management (VBM) by multinational entities in the Eastern Cape motor industry cluster (ECMIC)
- Authors: Blouw, Mbuyiselo Edwin
- Date: 2005
- Subjects: Corporations -- Valuation , Automobile industry and trade -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8550 , http://hdl.handle.net/10948/421 , Corporations -- Valuation , Automobile industry and trade -- South Africa
- Description: Management’s response to shareholders’ return on investment as a priority occurs in an increasingly dynamic environment. Accompanying these activities is the need to realign responsibilities and to allocate scarce resources effectively. This is done in order to ensure that companies achieve global competitiveness and increase shareholders’ return on investment. Against this backdrop, local industry needs to find new methods or strategies in order to achieve world-class competitiveness, and to be able to access foreign investment. One way to achieve these goals is through Value Based Management (VBM). The objective of this study is to evaluate the strategic intent of Multinational Entities in applying VBM to increase shareholders’ return on investment. Based on the study, certain factors are critical to ensure the success of VBM. A postal survey to managers in the motor manufacturing and component manufacturing companies was conducted to check the managers’ familiarity with VBM, and their scope, and usage of VBM; and, based on the finding, to evaluate the impact of VBM on companies’ results. The empirical finding was compared with a literature review, and the following findings were made: There is a strong understanding and application of the VBM principle on the part of local entities with Foreign Direct Investment (FDI); Departmental performance is critical to an entity’s overall performance; Based on the study, 23 per cent of the respondents use Economic Value Added (EVA) as an internal reporting measure, and an average of 19 per cent use other metrics; A total of 89 per cent of respondents indicated that they strongly agree with the use of incentives for motivation. The above-mentioned points were covered by means of 4-M framework ― that is: Measurement, Management, Motivation, and Mindset.
- Full Text:
- Date Issued: 2005
- Authors: Blouw, Mbuyiselo Edwin
- Date: 2005
- Subjects: Corporations -- Valuation , Automobile industry and trade -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8550 , http://hdl.handle.net/10948/421 , Corporations -- Valuation , Automobile industry and trade -- South Africa
- Description: Management’s response to shareholders’ return on investment as a priority occurs in an increasingly dynamic environment. Accompanying these activities is the need to realign responsibilities and to allocate scarce resources effectively. This is done in order to ensure that companies achieve global competitiveness and increase shareholders’ return on investment. Against this backdrop, local industry needs to find new methods or strategies in order to achieve world-class competitiveness, and to be able to access foreign investment. One way to achieve these goals is through Value Based Management (VBM). The objective of this study is to evaluate the strategic intent of Multinational Entities in applying VBM to increase shareholders’ return on investment. Based on the study, certain factors are critical to ensure the success of VBM. A postal survey to managers in the motor manufacturing and component manufacturing companies was conducted to check the managers’ familiarity with VBM, and their scope, and usage of VBM; and, based on the finding, to evaluate the impact of VBM on companies’ results. The empirical finding was compared with a literature review, and the following findings were made: There is a strong understanding and application of the VBM principle on the part of local entities with Foreign Direct Investment (FDI); Departmental performance is critical to an entity’s overall performance; Based on the study, 23 per cent of the respondents use Economic Value Added (EVA) as an internal reporting measure, and an average of 19 per cent use other metrics; A total of 89 per cent of respondents indicated that they strongly agree with the use of incentives for motivation. The above-mentioned points were covered by means of 4-M framework ― that is: Measurement, Management, Motivation, and Mindset.
- Full Text:
- Date Issued: 2005
An investigation of the factors that influence the decision-making of Chinese tourist travelling to South Africa
- Authors: Wan, Jiangtao
- Date: 2005
- Subjects: Tourism -- South Africa -- Decision making , Chinese -- Travel -- South Africa -- Attitudes
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9340 , http://hdl.handle.net/10948/411 , Tourism -- South Africa -- Decision making , Chinese -- Travel -- South Africa -- Attitudes
- Description: The growth of the Chinese economy represents a significant opportunity for global travel and tourism and it has raised the expectation that the South African tourism industry will explore and benefit from the Chinese outbound market growth. Since international travel and tourism is becoming a significant component of the South African economy, it is important to understand the factors that influence consumer decision-making in tourism. The main objective of this study was to determine the factors that influence the decision-making of Chinese tourists that travel to South Africa. The research gives a systemic review of the Chinese outbound market, starting with the Chinese outbound travel history, and the impact of the social-economic issues on Chinese travel and tourism. An overview is provided of the size, growth and the regulation of the Chinese outbound market, as well as the main characteristics of Chinese outbound tourists. The factors that influence decision-making are compartmentalised into two categories: internal and external factors. Internal and external factors relate to the concept that people travel due to the fact that they are pushed by their own internal forces and pulled by the external forces such as the social environment, reference groups, social class, the restrictions from government regulations and the attraction of travel destination countries. The empirical findings reflect that the factors that have the most significant impact on the decision-making process of Chinese outbound tourists travelling to South Africa are perception about safety, lack of knowledge about South Africa and a growth in the use of the Internet as a source of tourist information. The study also reflects a tendency towards individualism and a shift away from traditional group decision-making. Based on the findings of the empirical study, South Africa tourism needs to offer a safe travel environment, provide greater access to information featuring South Africa as a tourist destination, and offer discounted travel packages
- Full Text:
- Date Issued: 2005
- Authors: Wan, Jiangtao
- Date: 2005
- Subjects: Tourism -- South Africa -- Decision making , Chinese -- Travel -- South Africa -- Attitudes
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9340 , http://hdl.handle.net/10948/411 , Tourism -- South Africa -- Decision making , Chinese -- Travel -- South Africa -- Attitudes
- Description: The growth of the Chinese economy represents a significant opportunity for global travel and tourism and it has raised the expectation that the South African tourism industry will explore and benefit from the Chinese outbound market growth. Since international travel and tourism is becoming a significant component of the South African economy, it is important to understand the factors that influence consumer decision-making in tourism. The main objective of this study was to determine the factors that influence the decision-making of Chinese tourists that travel to South Africa. The research gives a systemic review of the Chinese outbound market, starting with the Chinese outbound travel history, and the impact of the social-economic issues on Chinese travel and tourism. An overview is provided of the size, growth and the regulation of the Chinese outbound market, as well as the main characteristics of Chinese outbound tourists. The factors that influence decision-making are compartmentalised into two categories: internal and external factors. Internal and external factors relate to the concept that people travel due to the fact that they are pushed by their own internal forces and pulled by the external forces such as the social environment, reference groups, social class, the restrictions from government regulations and the attraction of travel destination countries. The empirical findings reflect that the factors that have the most significant impact on the decision-making process of Chinese outbound tourists travelling to South Africa are perception about safety, lack of knowledge about South Africa and a growth in the use of the Internet as a source of tourist information. The study also reflects a tendency towards individualism and a shift away from traditional group decision-making. Based on the findings of the empirical study, South Africa tourism needs to offer a safe travel environment, provide greater access to information featuring South Africa as a tourist destination, and offer discounted travel packages
- Full Text:
- Date Issued: 2005
Establishing an information security culture in organizations : an outcomes based education approach
- Van Niekerk, Johannes Frederick
- Authors: Van Niekerk, Johannes Frederick
- Date: 2005
- Subjects: Computer security , Management information systems -- Security measures , Competency-based education
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9742 , http://hdl.handle.net/10948/164 , Computer security , Management information systems -- Security measures , Competency-based education
- Description: Information security is crucial to the continuous well-being of modern orga- nizations. Humans play a signfiicant role in the processes needed to secure an organization's information resources. Without an adequate level of user co-operation and knowledge, many security techniques are liable to be misused or misinterpreted by users. This may result in an adequate security measure becoming inadequate. It is therefor necessary to educate the orga- nization's employees regarding information security and also to establish a corporate sub-culture of information security in the organization, which will ensure that the employees have the correct attitude towards their security responsibilities. Current information security education programs fails to pay su±cient attention to the behavioral sciences. There also exist a lack of knowledge regarding the principles, and processes, that would be needed for the establishment of an corporate sub-culture, specific to information security. Without both the necessary knowledge, and the desired attitude amongst the employee, it will be impossible to guarantee that the organi- zation's information resources are secure. It would therefor make sense to address both these dimensions to the human factor in information security, using a single integrated, holistic approach. This dissertation presents such an approach, which is based on an integration of sound behavioral theories.
- Full Text:
- Date Issued: 2005
Establishing an information security culture in organizations : an outcomes based education approach
- Authors: Van Niekerk, Johannes Frederick
- Date: 2005
- Subjects: Computer security , Management information systems -- Security measures , Competency-based education
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9742 , http://hdl.handle.net/10948/164 , Computer security , Management information systems -- Security measures , Competency-based education
- Description: Information security is crucial to the continuous well-being of modern orga- nizations. Humans play a signfiicant role in the processes needed to secure an organization's information resources. Without an adequate level of user co-operation and knowledge, many security techniques are liable to be misused or misinterpreted by users. This may result in an adequate security measure becoming inadequate. It is therefor necessary to educate the orga- nization's employees regarding information security and also to establish a corporate sub-culture of information security in the organization, which will ensure that the employees have the correct attitude towards their security responsibilities. Current information security education programs fails to pay su±cient attention to the behavioral sciences. There also exist a lack of knowledge regarding the principles, and processes, that would be needed for the establishment of an corporate sub-culture, specific to information security. Without both the necessary knowledge, and the desired attitude amongst the employee, it will be impossible to guarantee that the organi- zation's information resources are secure. It would therefor make sense to address both these dimensions to the human factor in information security, using a single integrated, holistic approach. This dissertation presents such an approach, which is based on an integration of sound behavioral theories.
- Full Text:
- Date Issued: 2005
On the growth and characterisation of AIGaN alloys for optoelectronic applications
- Authors: James, Grant Robert
- Date: 2005
- Subjects: Gallium nitride -- Electric properties , Photoluminescence
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8824 , vital:26433
- Description: In this study the growth and characterisation of undoped and Si-doped AlxGa1-xN has been performed. The layers were grown using low-pressure metalorganic vapour phase deposition (MOCVD) on sapphire substrates. The optical and electrical properties of the AlxGa1-xN layers were studied using variable temperature Hall effect and photoluminescence measurements. AlxGa1-xN layers were grown over the entire composition range. Room temperature ultraviolet (UV) transmission measurements showed that the material quality was very good for layers with an Al content, x, of 0 _ x _ 0.5. However, the quality of layers of higher composition was seen to rapidly decrease with increasing x. The electrical and optical properties of AlxGa1-xN with x < 0.5 were also good, comparable to those reported on in literature. The study of the Si-doping of AlxGa1-xN was performed in two parts; firstly a series of Al0.23Ga0.77N samples was grown in which the doping level was increased from zero to n _ 3 × 1018 cm-3. A similar, albeit a less rigorous, study was performed for Al0.41Ga0.59N and Al0.5Ga0.5N. A second series of samples was then grown in which the doping level was kept constant, while the Al content was incrementally increased. Room temperature Hall effect measurements performed on Si-doped Al0.23Ga0.77N showed that the electron concentration did not scale linearly with the silane flow, as was the case in GaN. It was also seen that the electron mobility of the layers increased with slight Si-doping, possibly due to an improvement in the crystalline quality and/or a change in the conduction mechanism. It was also found that at higher compositions (x = 0.41 and 0.50) an increase in the doping level resulted in an increase in the mobility. Variable temperature Hall effect and photoluminescence measurements, performed on the Al0.23Ga0.77N samples, revealed a good correlation between the first PL activation energy E1 and the donor activation energy ED, prompting the conclusion that the first PL recombination channel in AlxGa1-xN is due to the delocalisation of excitons bound at neutral Si donors. Furthermore, E1 and ED were seen to decrease with n1/3, as is the case for GaN and other semiconductor materials. It was also observed that strong exciton localisation occurs in slightly Si-doped material, with the amount of localization becoming less at higher doping levels. Possible mechanisms responsible for the second PL recombination channel of activation energy E2 were also proposed. The electrical and optical properties of the second set of AlxGa1-xN samples was then studied. The PL properties of undoped AlxGa1-xN were typical of a homogeneous alloy system, with the increase in the PL FWHM and exciton localisation energies with x following the trend predicted by alloy disorder theory. The variation of the band gap energy with the Al content could not, however, be fitted over the entire composition range using a single bowing parameter. It was proposed that this was due either to an effect of the 9 7 valence band crossover, or due to exciton localisation at alloy disorder and/or impurities. As was the case for GaN and Al0.23Ga0.77N, all undoped material was highly resistive. As was mentioned earlier, the exciton localisation energies increased according to alloy disorder theory in undoped AlxGa1-xN. In the doped samples, however, a large increase in the donor localisation energy was measured for x > 0.3. The possibility that Si could become a DX-centre in AlxGa1-xN was then investigated. However, Hall effect measurements showed that the Si activation energy increased in good agreement with the model of a shallow effective mass state donor, with no sudden increase in ED being observed up to x = 0.4. It was then suggested that the increase in the E1 and E2 activation energies, as well as the exciton localisation energies, could be due to the 9 7 valence band crossover, which occurs at roughly the same composition. However, due to the scarcity of reports on the valence band structure in AlxGa1-xN no conclusions could be made at this stage as to the effect of the 9 7 valence band crossover on the PL properties of AlxGa1-xN.
- Full Text:
- Date Issued: 2005
- Authors: James, Grant Robert
- Date: 2005
- Subjects: Gallium nitride -- Electric properties , Photoluminescence
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8824 , vital:26433
- Description: In this study the growth and characterisation of undoped and Si-doped AlxGa1-xN has been performed. The layers were grown using low-pressure metalorganic vapour phase deposition (MOCVD) on sapphire substrates. The optical and electrical properties of the AlxGa1-xN layers were studied using variable temperature Hall effect and photoluminescence measurements. AlxGa1-xN layers were grown over the entire composition range. Room temperature ultraviolet (UV) transmission measurements showed that the material quality was very good for layers with an Al content, x, of 0 _ x _ 0.5. However, the quality of layers of higher composition was seen to rapidly decrease with increasing x. The electrical and optical properties of AlxGa1-xN with x < 0.5 were also good, comparable to those reported on in literature. The study of the Si-doping of AlxGa1-xN was performed in two parts; firstly a series of Al0.23Ga0.77N samples was grown in which the doping level was increased from zero to n _ 3 × 1018 cm-3. A similar, albeit a less rigorous, study was performed for Al0.41Ga0.59N and Al0.5Ga0.5N. A second series of samples was then grown in which the doping level was kept constant, while the Al content was incrementally increased. Room temperature Hall effect measurements performed on Si-doped Al0.23Ga0.77N showed that the electron concentration did not scale linearly with the silane flow, as was the case in GaN. It was also seen that the electron mobility of the layers increased with slight Si-doping, possibly due to an improvement in the crystalline quality and/or a change in the conduction mechanism. It was also found that at higher compositions (x = 0.41 and 0.50) an increase in the doping level resulted in an increase in the mobility. Variable temperature Hall effect and photoluminescence measurements, performed on the Al0.23Ga0.77N samples, revealed a good correlation between the first PL activation energy E1 and the donor activation energy ED, prompting the conclusion that the first PL recombination channel in AlxGa1-xN is due to the delocalisation of excitons bound at neutral Si donors. Furthermore, E1 and ED were seen to decrease with n1/3, as is the case for GaN and other semiconductor materials. It was also observed that strong exciton localisation occurs in slightly Si-doped material, with the amount of localization becoming less at higher doping levels. Possible mechanisms responsible for the second PL recombination channel of activation energy E2 were also proposed. The electrical and optical properties of the second set of AlxGa1-xN samples was then studied. The PL properties of undoped AlxGa1-xN were typical of a homogeneous alloy system, with the increase in the PL FWHM and exciton localisation energies with x following the trend predicted by alloy disorder theory. The variation of the band gap energy with the Al content could not, however, be fitted over the entire composition range using a single bowing parameter. It was proposed that this was due either to an effect of the 9 7 valence band crossover, or due to exciton localisation at alloy disorder and/or impurities. As was the case for GaN and Al0.23Ga0.77N, all undoped material was highly resistive. As was mentioned earlier, the exciton localisation energies increased according to alloy disorder theory in undoped AlxGa1-xN. In the doped samples, however, a large increase in the donor localisation energy was measured for x > 0.3. The possibility that Si could become a DX-centre in AlxGa1-xN was then investigated. However, Hall effect measurements showed that the Si activation energy increased in good agreement with the model of a shallow effective mass state donor, with no sudden increase in ED being observed up to x = 0.4. It was then suggested that the increase in the E1 and E2 activation energies, as well as the exciton localisation energies, could be due to the 9 7 valence band crossover, which occurs at roughly the same composition. However, due to the scarcity of reports on the valence band structure in AlxGa1-xN no conclusions could be made at this stage as to the effect of the 9 7 valence band crossover on the PL properties of AlxGa1-xN.
- Full Text:
- Date Issued: 2005
Developing a model for establishing, implementing, and maintaining learnerships in South Africa
- Authors: Hamlet, Brian
- Date: 2005
- Subjects: Employees -- Training of -- South Africa , Experiential learning -- South Africa , Education, Cooperative -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9377 , http://hdl.handle.net/10948/156 , Employees -- Training of -- South Africa , Experiential learning -- South Africa , Education, Cooperative -- South Africa
- Description: The research problem in this study was to identify how successful the methods are that organisations use within the Manufacturing Engineering and Related Services Education and Training Authorities (MERSETA) chambers to develop, implement and maintain learnerships. To achieve this aim a literature examination to determine the aspects of workplace learning were explored, including the various perspectives of learning, together with an investigation into workplace learning. Further, apprenticeships, traineeships, learnerships were discussed; including the concepts vocational education and training standards, and competence explored. Finally a process model for effective learnership implementation was presented based on international approaches together with the South African models and current practices. - v - The process learnership model served as a basis for drawing up a survey questionnaire to establish the extent to which organisations agreed or disagreed with the learnership model developed. The survey was limited to the “automobile” and “new tyre” chambers of the MERSETA. The results obtained from the empirical study indicted a high degree of agreement with the process model for effective learnership implementation. The results obtained from the quantitative data, and qualitative data were used to adapt the learnership process model, and produce a six-phase integrated learnership model. From the survey it become evident that organisations needed to be sensitised and educated as to learnerships before considering more seriously learnership implementation. Further, it emerged that learnerships cannot only be effective within a process approach, and that it should also take place within a positive “organisational learning culture”. Organisations and Sector Education and Training Authorities (SETAs) can now use the six-phase integrated learnership model with confidence, as there was a high degree of agreement with the learnership model that was developed as part of this research study. The six-phase integrated learnership model has been comprehensively developed and surveyed by organisations that are currently implementing learnerships on a large scale. Organisations and SETAs can now give effect to the Skills Development Act No. 97 of 1998, and contribute to the National skills Development Strategy of 2001, which aims to improve the workplace skills of all South Africans.
- Full Text:
- Date Issued: 2005
- Authors: Hamlet, Brian
- Date: 2005
- Subjects: Employees -- Training of -- South Africa , Experiential learning -- South Africa , Education, Cooperative -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9377 , http://hdl.handle.net/10948/156 , Employees -- Training of -- South Africa , Experiential learning -- South Africa , Education, Cooperative -- South Africa
- Description: The research problem in this study was to identify how successful the methods are that organisations use within the Manufacturing Engineering and Related Services Education and Training Authorities (MERSETA) chambers to develop, implement and maintain learnerships. To achieve this aim a literature examination to determine the aspects of workplace learning were explored, including the various perspectives of learning, together with an investigation into workplace learning. Further, apprenticeships, traineeships, learnerships were discussed; including the concepts vocational education and training standards, and competence explored. Finally a process model for effective learnership implementation was presented based on international approaches together with the South African models and current practices. - v - The process learnership model served as a basis for drawing up a survey questionnaire to establish the extent to which organisations agreed or disagreed with the learnership model developed. The survey was limited to the “automobile” and “new tyre” chambers of the MERSETA. The results obtained from the empirical study indicted a high degree of agreement with the process model for effective learnership implementation. The results obtained from the quantitative data, and qualitative data were used to adapt the learnership process model, and produce a six-phase integrated learnership model. From the survey it become evident that organisations needed to be sensitised and educated as to learnerships before considering more seriously learnership implementation. Further, it emerged that learnerships cannot only be effective within a process approach, and that it should also take place within a positive “organisational learning culture”. Organisations and Sector Education and Training Authorities (SETAs) can now use the six-phase integrated learnership model with confidence, as there was a high degree of agreement with the learnership model that was developed as part of this research study. The six-phase integrated learnership model has been comprehensively developed and surveyed by organisations that are currently implementing learnerships on a large scale. Organisations and SETAs can now give effect to the Skills Development Act No. 97 of 1998, and contribute to the National skills Development Strategy of 2001, which aims to improve the workplace skills of all South Africans.
- Full Text:
- Date Issued: 2005
The identification of a model to promote intrapreneurship in an automotive component company
- Authors: Du Preez, Catherine Amanda
- Date: 2005
- Subjects: Entrepreneurship , Automobile industry and trade -- South Africa , Organizational change
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8549 , http://hdl.handle.net/10948/423 , Entrepreneurship , Automobile industry and trade -- South Africa , Organizational change
- Description: South African organisations are facing a new era of intense global competition. The modern business world is characterised by change and this change presents both challenges and opportunities. As a result, organisations have to become more responsive to change by continuous, rapid and cost-effective innovation through integrating the strengths of the entrepreneurial small firm, such as creativity, flexibility and innovativeness, with the market power and resources of the large firm. Due to the dynamic nature of the automotive industry, it is vital that South African organisations and management identify creativity and innovation as the main sources of sustainable competitive advantage. Sustained competitive advantage is derived from consistently satisfying customers’ wants and needs through innovation. An intrapreneurial philosophy is of key importance to an organisation’s corporate strategy, ensuring that entrepreneurial values are incorporated into the culture of the organisation. This study took place within an automotive component company operating in the Eastern Cape. Based on the theoretical findings of the literature study a questionnaire was developed and distributed to all employees of the company. The objective of the questionnaire was to measure the prevalence of intrapreneurship within the company and based on the findings of the literature study, recommendations on the structure, systems, culture and management styles of the organisation were made. Finally, a model was developed that identifies the importance of innovation, customer-solution centeredness and being market driven as core strategic values.
- Full Text:
- Date Issued: 2005
- Authors: Du Preez, Catherine Amanda
- Date: 2005
- Subjects: Entrepreneurship , Automobile industry and trade -- South Africa , Organizational change
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8549 , http://hdl.handle.net/10948/423 , Entrepreneurship , Automobile industry and trade -- South Africa , Organizational change
- Description: South African organisations are facing a new era of intense global competition. The modern business world is characterised by change and this change presents both challenges and opportunities. As a result, organisations have to become more responsive to change by continuous, rapid and cost-effective innovation through integrating the strengths of the entrepreneurial small firm, such as creativity, flexibility and innovativeness, with the market power and resources of the large firm. Due to the dynamic nature of the automotive industry, it is vital that South African organisations and management identify creativity and innovation as the main sources of sustainable competitive advantage. Sustained competitive advantage is derived from consistently satisfying customers’ wants and needs through innovation. An intrapreneurial philosophy is of key importance to an organisation’s corporate strategy, ensuring that entrepreneurial values are incorporated into the culture of the organisation. This study took place within an automotive component company operating in the Eastern Cape. Based on the theoretical findings of the literature study a questionnaire was developed and distributed to all employees of the company. The objective of the questionnaire was to measure the prevalence of intrapreneurship within the company and based on the findings of the literature study, recommendations on the structure, systems, culture and management styles of the organisation were made. Finally, a model was developed that identifies the importance of innovation, customer-solution centeredness and being market driven as core strategic values.
- Full Text:
- Date Issued: 2005
The development of motivational strategies for public sector workers in Kenya
- Authors: Chepkilot, Ronald Kiprop
- Date: 2005
- Subjects: Public administration -- Kenya , Employee motivation , Civil service -- Kenya -- Personnel management
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9380 , http://hdl.handle.net/10948/161 , Public administration -- Kenya , Employee motivation , Civil service -- Kenya -- Personnel management
- Description: The purpose of this study was to develop motivational strategies for motivating public sector workers in Kenya. To achieve this objective the following procedure was followed: • An examination of the public service was undertaken and the following factors were considered: The history of the public service; Past government reform programmes; The problem of corruption; Future government reform programmes; and The motivational climate in the service. iv • A literature survey was conducted on the approaches used by organisations in motivating employees. The findings were used to develop a motivational strategy model. On the basis of the strategies in the model, a questionnaire was developed for the empirical research study. • The empirical study was undertaken to examine the level of motivation in the public service and to identify the motivational strategies currently used in the public service in Kenya. The study also sought to determine the extent to which public sector managers agreed or disagreed that the motivational strategies developed by the study would be effective in motivating employees in their organisations. The results of the empirical study were incorporated into the integrated motivational strategy model presented in chapter six. The study established that the level of motivation among the public sector workers was extremely low. According to the research findings, 87 per cent of the respondents indicated that the level of motivation of employees in their organisation was low while 13 per cent indicated that it was high. It was also established that the climate in the public service was not conducive for motivating employees: the indicators were lack of job security; very low salaries; limited training and development opportunities; lack of career development programmes and lack of adequate working tools and equipment. It was further established that the government could no longer afford to make any substantial increases in salaries to the workers because the wage bill was extremely high at the level of 9.6 per cent of the GDP. It was observed that any further increases in salaries would v have a negative impact on the economy of the country. In view of the above, this study becomes extremely relevant as it suggests ways of enhancing the levels of motivation in the public service to improve service delivery in the public sector without allocation of vast financial resources. The study strongly recommends the application of the integrated motivational strategy model in its entirety; to enhance the level of employee’s motivation and work performance and achieve efficiency and effectiveness in service delivery. The study also recommends that further research be carried out to determine the effects of corruption on employee motivation and ways of eliminating the vice in the public service.
- Full Text:
- Date Issued: 2005
- Authors: Chepkilot, Ronald Kiprop
- Date: 2005
- Subjects: Public administration -- Kenya , Employee motivation , Civil service -- Kenya -- Personnel management
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9380 , http://hdl.handle.net/10948/161 , Public administration -- Kenya , Employee motivation , Civil service -- Kenya -- Personnel management
- Description: The purpose of this study was to develop motivational strategies for motivating public sector workers in Kenya. To achieve this objective the following procedure was followed: • An examination of the public service was undertaken and the following factors were considered: The history of the public service; Past government reform programmes; The problem of corruption; Future government reform programmes; and The motivational climate in the service. iv • A literature survey was conducted on the approaches used by organisations in motivating employees. The findings were used to develop a motivational strategy model. On the basis of the strategies in the model, a questionnaire was developed for the empirical research study. • The empirical study was undertaken to examine the level of motivation in the public service and to identify the motivational strategies currently used in the public service in Kenya. The study also sought to determine the extent to which public sector managers agreed or disagreed that the motivational strategies developed by the study would be effective in motivating employees in their organisations. The results of the empirical study were incorporated into the integrated motivational strategy model presented in chapter six. The study established that the level of motivation among the public sector workers was extremely low. According to the research findings, 87 per cent of the respondents indicated that the level of motivation of employees in their organisation was low while 13 per cent indicated that it was high. It was also established that the climate in the public service was not conducive for motivating employees: the indicators were lack of job security; very low salaries; limited training and development opportunities; lack of career development programmes and lack of adequate working tools and equipment. It was further established that the government could no longer afford to make any substantial increases in salaries to the workers because the wage bill was extremely high at the level of 9.6 per cent of the GDP. It was observed that any further increases in salaries would v have a negative impact on the economy of the country. In view of the above, this study becomes extremely relevant as it suggests ways of enhancing the levels of motivation in the public service to improve service delivery in the public sector without allocation of vast financial resources. The study strongly recommends the application of the integrated motivational strategy model in its entirety; to enhance the level of employee’s motivation and work performance and achieve efficiency and effectiveness in service delivery. The study also recommends that further research be carried out to determine the effects of corruption on employee motivation and ways of eliminating the vice in the public service.
- Full Text:
- Date Issued: 2005
The mining and visualisation of application services data
- Authors: Knoetze, Ronald Morgan
- Date: 2005
- Subjects: Data mining -- South Africa , Computer algorithms , Network performance (Telecommunication) -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10480 , http://hdl.handle.net/10948/451 , Data mining -- South Africa , Computer algorithms , Network performance (Telecommunication) -- Research -- South Africa
- Description: Many network monitoring tools do not provide sufficiently in-depth and useful reports on network usage, particularly in the domain of application services data. The optimisation of network performance is only possible if the networks are monitored effectively. Techniques that identify patterns of network usage can assist in the successful monitoring of network performance. The main goal of this research was to propose a model to mine and visualise application services data in order to support effective network management. To demonstrate the effectiveness of the model, a prototype, called NetPatterns, was developed using data for the Integrated Tertiary Software (ITS) application service collected by a network monitoring tool on the NMMU South Campus network. Three data mining algorithms for application services data were identified for the proposed model. The data mining algorithms used are classification (decision tree), clustering (K-Means) and association (correlation). Classifying application services data serves to categorise combinations of network attributes to highlight areas of poor network performance. The clustering of network attributes serves to indicate sparse and dense regions within the application services data. Association indicates the existence of any interesting relationships between different network attributes. Three visualisation techniques were selected to visualise the results of the data mining algorithms. The visualisation techniques selected were the organisation chart, bubble chart and scatterplots. Colour and a variety of other visual cues are used to complement the selected visualisation techniques. The effectiveness and usefulness of NetPatterns was determined by means of user testing. The results of the evaluation clearly show that the participants were highly satisfied with the visualisation of network usage presented by NetPatterns. All participants successfully completed the prescribed tasks and indicated that NetPatterns is a useful tool for the analysis of network usage patterns.
- Full Text:
- Date Issued: 2005
- Authors: Knoetze, Ronald Morgan
- Date: 2005
- Subjects: Data mining -- South Africa , Computer algorithms , Network performance (Telecommunication) -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10480 , http://hdl.handle.net/10948/451 , Data mining -- South Africa , Computer algorithms , Network performance (Telecommunication) -- Research -- South Africa
- Description: Many network monitoring tools do not provide sufficiently in-depth and useful reports on network usage, particularly in the domain of application services data. The optimisation of network performance is only possible if the networks are monitored effectively. Techniques that identify patterns of network usage can assist in the successful monitoring of network performance. The main goal of this research was to propose a model to mine and visualise application services data in order to support effective network management. To demonstrate the effectiveness of the model, a prototype, called NetPatterns, was developed using data for the Integrated Tertiary Software (ITS) application service collected by a network monitoring tool on the NMMU South Campus network. Three data mining algorithms for application services data were identified for the proposed model. The data mining algorithms used are classification (decision tree), clustering (K-Means) and association (correlation). Classifying application services data serves to categorise combinations of network attributes to highlight areas of poor network performance. The clustering of network attributes serves to indicate sparse and dense regions within the application services data. Association indicates the existence of any interesting relationships between different network attributes. Three visualisation techniques were selected to visualise the results of the data mining algorithms. The visualisation techniques selected were the organisation chart, bubble chart and scatterplots. Colour and a variety of other visual cues are used to complement the selected visualisation techniques. The effectiveness and usefulness of NetPatterns was determined by means of user testing. The results of the evaluation clearly show that the participants were highly satisfied with the visualisation of network usage presented by NetPatterns. All participants successfully completed the prescribed tasks and indicated that NetPatterns is a useful tool for the analysis of network usage patterns.
- Full Text:
- Date Issued: 2005
The learning styles of first year university students
- Authors: Vawda, Aamena
- Date: 2005
- Subjects: Learning, Psychology of , College students -- South Africa -- Evaluation , Learning ability
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9849 , http://hdl.handle.net/10948/358 , http://hdl.handle.net/10948/d1005817 , Learning, Psychology of , College students -- South Africa -- Evaluation , Learning ability
- Description: There has been a shift in the South African education system from a purely grade-oriented system to that of a learner-centred outcome-based system of education which challenges higher educational institutions and their faculties to adjust their goals to this system. In South Africa there is evidence of poor academic performance at higher education institutions. Among other things, noncognitive factors may be important mediators of academic success. With the expansion of higher education and the increased emphasis on access, retention and life-long learning, it is a good reason to explore the nature of different learning styles (Healey & Jenkins, 2000). Learning styles and personality types has been identified as significant predictors of academic performance. The present study aimed to contribute to this body of research in general and to Kolb’s (1981) theory of experiential learning and his conceptualisation of learning styles in particular. The aims of the study were to explore and describe the learning styles of first year university students (Aim 1), to explore and describe the learning styles of first year university students per faculty (Aim 2), and to explore the relationship between learning styles and academic performance for students in the various faculties (Aim 3). The study used an explorative descriptive and correlational research method and was conducted within a quantitative framework. Participants were selected using a non-probability convenience sampling technique. The sample was comprised of 391 first year university students to whom Kolb’s Learning Style Indicator was administered as part of the Explore programme during orientation week. Descriptive statistics were used in order to explore and describe the learning style of the learners for the sample as a whole and per faculty. Data for the learning styles and academic performance categories were cross tabulated so as to comment on the relationship between learning styles and academic performance per faculty. Small cell sizes made it impossible to analyse the latter data statistically. Across the six faculties the Accommodator learning style was the most represented, followed by the Diverger learning style. No significant relationship was found between learning styles and academic performance. The implications of the findings for counselling and teaching students are highlighted and suggestions to expand the research through using larger samples are also made.
- Full Text:
- Date Issued: 2005
- Authors: Vawda, Aamena
- Date: 2005
- Subjects: Learning, Psychology of , College students -- South Africa -- Evaluation , Learning ability
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9849 , http://hdl.handle.net/10948/358 , http://hdl.handle.net/10948/d1005817 , Learning, Psychology of , College students -- South Africa -- Evaluation , Learning ability
- Description: There has been a shift in the South African education system from a purely grade-oriented system to that of a learner-centred outcome-based system of education which challenges higher educational institutions and their faculties to adjust their goals to this system. In South Africa there is evidence of poor academic performance at higher education institutions. Among other things, noncognitive factors may be important mediators of academic success. With the expansion of higher education and the increased emphasis on access, retention and life-long learning, it is a good reason to explore the nature of different learning styles (Healey & Jenkins, 2000). Learning styles and personality types has been identified as significant predictors of academic performance. The present study aimed to contribute to this body of research in general and to Kolb’s (1981) theory of experiential learning and his conceptualisation of learning styles in particular. The aims of the study were to explore and describe the learning styles of first year university students (Aim 1), to explore and describe the learning styles of first year university students per faculty (Aim 2), and to explore the relationship between learning styles and academic performance for students in the various faculties (Aim 3). The study used an explorative descriptive and correlational research method and was conducted within a quantitative framework. Participants were selected using a non-probability convenience sampling technique. The sample was comprised of 391 first year university students to whom Kolb’s Learning Style Indicator was administered as part of the Explore programme during orientation week. Descriptive statistics were used in order to explore and describe the learning style of the learners for the sample as a whole and per faculty. Data for the learning styles and academic performance categories were cross tabulated so as to comment on the relationship between learning styles and academic performance per faculty. Small cell sizes made it impossible to analyse the latter data statistically. Across the six faculties the Accommodator learning style was the most represented, followed by the Diverger learning style. No significant relationship was found between learning styles and academic performance. The implications of the findings for counselling and teaching students are highlighted and suggestions to expand the research through using larger samples are also made.
- Full Text:
- Date Issued: 2005
The unfair labour practice relating to benefits
- Authors: Tshiki, Pakamisa Washington
- Date: 2005
- Subjects: Employee fringe benefits -- Law and legislation -- South Africa , Unfair labour practices -- South Africa , Discrimination in employment -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10189 , http://hdl.handle.net/10948/386 , Employee fringe benefits -- Law and legislation -- South Africa , Unfair labour practices -- South Africa , Discrimination in employment -- South Africa
- Description: At the outset of this treatise the development of the unfair labour practice is traced. The point is made that common law knows nothing about fairness and it is pointed out that the concept was introduced as a statutory concept in 1979. In 1995 the development of unfair labour practices since 1979 was relied upon to provide a list of unfair labour practices. The main thrust of the treatise concerns an evaluation of an unfair labour practice relating to benefits – listed presently in section 186(2) of the Labour Relations Act. Reference is made to Industrial Court cases and case law since 1996 is considered and commented upon. In particular, the issue of remuneration not being a benefit, and the fact that interest disputes are not justiciable as unfair labour practices for instance are canvassed.
- Full Text:
- Date Issued: 2005
- Authors: Tshiki, Pakamisa Washington
- Date: 2005
- Subjects: Employee fringe benefits -- Law and legislation -- South Africa , Unfair labour practices -- South Africa , Discrimination in employment -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10189 , http://hdl.handle.net/10948/386 , Employee fringe benefits -- Law and legislation -- South Africa , Unfair labour practices -- South Africa , Discrimination in employment -- South Africa
- Description: At the outset of this treatise the development of the unfair labour practice is traced. The point is made that common law knows nothing about fairness and it is pointed out that the concept was introduced as a statutory concept in 1979. In 1995 the development of unfair labour practices since 1979 was relied upon to provide a list of unfair labour practices. The main thrust of the treatise concerns an evaluation of an unfair labour practice relating to benefits – listed presently in section 186(2) of the Labour Relations Act. Reference is made to Industrial Court cases and case law since 1996 is considered and commented upon. In particular, the issue of remuneration not being a benefit, and the fact that interest disputes are not justiciable as unfair labour practices for instance are canvassed.
- Full Text:
- Date Issued: 2005
Dimensions of guest house service: perceptions of owners and expectations of business travellers
- Wang, Yi
- Authors: Wang, Yi
- Date: 2005
- Subjects: Hospitality industry -- Customer relations , Boardinghouses -- Customer services -- South Africa , Consumer satisfaction -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9354 , http://hdl.handle.net/10948/d1006215 , Hospitality industry -- Customer relations , Boardinghouses -- Customer services -- South Africa , Consumer satisfaction -- South Africa
- Description: The need for successful management of a guest house in the increasingly competitive hospitality industry in South Africa, compels guest house owners to understand their customers’ needs and deliver service of acceptable quality. The objective of the research is to find out what business travellers expect from a guest house and how these expectations compare with the perceptions of guest house owners in Port Elizabeth. Conclusions drawn from this research would also benefit guest house owners in other parts of the country. A literature review was conducted to provide an understanding of the nature of service and the role “evidence of service” can play in the perception of quality. The empirical study aimed at comparing business travellers’ expectations of guest house service with guest house owners’ perceptions of their guests’ expectations. The empirical findings showed that business travellers deemed secure parking and professionalism of staff as the most important attributes, while guest house owners thought it would be friendliness of front desk staff and efficient handling of complaints. Moreover, both groups indicated that cleanliness of rooms and services performed by staff adequately the first time, were of particular importance. It was also found that the importance rating of the different service dimensions were not significantly influenced by the business travellers’ gender, managerial position, nights of stay or by the guest house grading. The study proposes that guest house owners continue to focus on strategies for training and developing competent employees, simplify the steps of service delivery and improve on the standards of the servcie to ensure that business facilities are in line with the expectations of business travelers.
- Full Text:
- Date Issued: 2005
- Authors: Wang, Yi
- Date: 2005
- Subjects: Hospitality industry -- Customer relations , Boardinghouses -- Customer services -- South Africa , Consumer satisfaction -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9354 , http://hdl.handle.net/10948/d1006215 , Hospitality industry -- Customer relations , Boardinghouses -- Customer services -- South Africa , Consumer satisfaction -- South Africa
- Description: The need for successful management of a guest house in the increasingly competitive hospitality industry in South Africa, compels guest house owners to understand their customers’ needs and deliver service of acceptable quality. The objective of the research is to find out what business travellers expect from a guest house and how these expectations compare with the perceptions of guest house owners in Port Elizabeth. Conclusions drawn from this research would also benefit guest house owners in other parts of the country. A literature review was conducted to provide an understanding of the nature of service and the role “evidence of service” can play in the perception of quality. The empirical study aimed at comparing business travellers’ expectations of guest house service with guest house owners’ perceptions of their guests’ expectations. The empirical findings showed that business travellers deemed secure parking and professionalism of staff as the most important attributes, while guest house owners thought it would be friendliness of front desk staff and efficient handling of complaints. Moreover, both groups indicated that cleanliness of rooms and services performed by staff adequately the first time, were of particular importance. It was also found that the importance rating of the different service dimensions were not significantly influenced by the business travellers’ gender, managerial position, nights of stay or by the guest house grading. The study proposes that guest house owners continue to focus on strategies for training and developing competent employees, simplify the steps of service delivery and improve on the standards of the servcie to ensure that business facilities are in line with the expectations of business travelers.
- Full Text:
- Date Issued: 2005
Introducing hippocratic log files for personal privacy control
- Authors: Rutherford, Andrew
- Date: 2005
- Subjects: Computer security , Internet -- Security measures
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9743 , http://hdl.handle.net/10948/171 , Computer security , Internet -- Security measures
- Description: The rapid growth of the Internet has served to intensify existing privacy concerns of the individual, to the point that privacy is the number one concern amongst Internet users today. Tools exist that can provide users with a choice of anonymity or pseudonymity. However, many Web transactions require the release of personally identifying information, thus rendering such tools infeasible in many instances. Since it is then a given that users are often required to release personal information, which could be recorded, it follows that they require a greater degree of control over the information they release. Hippocratic databases, designed by Agrawal, Kiernan, Srikant, and Xu (2002), aim to give users greater control over information stored in a data- base. Their design was inspired by the medical Hippocratic oath, and makes data privacy protection a fundamental responsibility of the database itself. To achieve the privacy of data, Hippocratic databases are governed by 10 key privacy principles. This dissertation argues, that asides from a few challenges, the 10 prin- ciples of Hippocratic databases can be applied to log ¯les. This argument is supported by presenting a high-level functional view of a Hippocratic log file architecture. This architecture focuses on issues that highlight the con- trol users gain over their personal information that is collected in log files. By presenting a layered view of the aforementioned architecture, it was, fur- thermore, possible to provide greater insight into the major processes that would be at work in a Hippocratic log file implementation. An exploratory prototype served to understand and demonstrate certain of the architectural components of Hippocratic log files. This dissertation, thus, makes a contribution to the ideal of providing users with greater control over their personal information, by proposing the use of Hippocratic logfiles.
- Full Text:
- Date Issued: 2005
- Authors: Rutherford, Andrew
- Date: 2005
- Subjects: Computer security , Internet -- Security measures
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9743 , http://hdl.handle.net/10948/171 , Computer security , Internet -- Security measures
- Description: The rapid growth of the Internet has served to intensify existing privacy concerns of the individual, to the point that privacy is the number one concern amongst Internet users today. Tools exist that can provide users with a choice of anonymity or pseudonymity. However, many Web transactions require the release of personally identifying information, thus rendering such tools infeasible in many instances. Since it is then a given that users are often required to release personal information, which could be recorded, it follows that they require a greater degree of control over the information they release. Hippocratic databases, designed by Agrawal, Kiernan, Srikant, and Xu (2002), aim to give users greater control over information stored in a data- base. Their design was inspired by the medical Hippocratic oath, and makes data privacy protection a fundamental responsibility of the database itself. To achieve the privacy of data, Hippocratic databases are governed by 10 key privacy principles. This dissertation argues, that asides from a few challenges, the 10 prin- ciples of Hippocratic databases can be applied to log ¯les. This argument is supported by presenting a high-level functional view of a Hippocratic log file architecture. This architecture focuses on issues that highlight the con- trol users gain over their personal information that is collected in log files. By presenting a layered view of the aforementioned architecture, it was, fur- thermore, possible to provide greater insight into the major processes that would be at work in a Hippocratic log file implementation. An exploratory prototype served to understand and demonstrate certain of the architectural components of Hippocratic log files. This dissertation, thus, makes a contribution to the ideal of providing users with greater control over their personal information, by proposing the use of Hippocratic logfiles.
- Full Text:
- Date Issued: 2005
The subjective well-being of divorced single custodial parents
- Authors: Henry, Jaci Lee
- Date: 2005
- Subjects: Single parents -- South Africa , Divorced parents -- South Africa , Self-actualization (Psychology)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9841 , http://hdl.handle.net/10948/368 , Single parents -- South Africa , Divorced parents -- South Africa , Self-actualization (Psychology)
- Description: As the divorce rate consistently rises, the occurrence of single parent families are becoming increasingly prevalent. Despite the marked increase in single custodial parents, research on this population (and more importantly, into the positive aspects such as their subjective well-being) has been neglected. Over the past three decades, psychologists have shifted the emphasis of their research from examining demographic and pathogenic factors to a positive psychology framework focusing on personality and resilience. The general aim of this study was to explore and describe the subjective wellbeing, including satisfaction with life and general happiness, of divorced, single custodial parents. In addition, this study aimed to identify potential patterns among the aspects of subjective well-being investigated and aimed to explore the relationships between these patterns. Thirty-five participants were included for participation in this study by means of non-probability, purposive sampling. The research measures included a biographical questionnaire, the Satisfaction with Life Scale (SWLS) and Affectometer-2 Scale (AFM-2). The data were analysed by the researcher and an independent statistician in terms of descriptive statistics and cluster analysis, or according to content analysis. This reflects a triangulation data collection and analysis method. Key findings included the following: The results of the SWLS indicated that the majority of participants reported being slightly dissatisfied with their lives. The results of the AFM-2 indicated that the participants generally had high levels of positive affect, and low levels of negative affect. However, the participants’ overall levels of happiness were still relatively low. A four cluster solution was obtained, with the clusters being significantly different from each other on all input variables. The first cluster experienced high levels of positive affect, low levels of negative affect, and high levels of overall happiness. The second cluster experienced predominantly slight dissatisfaction with their lives, high levels of positive affect, low levels of negative affect, and slightly low levels of overall happiness. The third cluster reported mostly dissatisfaction with their lives, low levels of positive affect, high levels of negative affect, and very low levels of overall happiness. The fourth cluster experienced predominantly slight satisfaction with xi life, slightly high levels of positive affect, neutral levels of negative affect, and low levels of overall happiness. It appeared that clusters containing participants who were satisfied with their jobs, were involved in a personal relationship and who participated in leisure activities, all experienced higher levels of subjective well-being. Overall, this study emphasises the value of and the need for South African research on the subjective wellbeing of divorced, single custodial parents.
- Full Text:
- Date Issued: 2005
- Authors: Henry, Jaci Lee
- Date: 2005
- Subjects: Single parents -- South Africa , Divorced parents -- South Africa , Self-actualization (Psychology)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9841 , http://hdl.handle.net/10948/368 , Single parents -- South Africa , Divorced parents -- South Africa , Self-actualization (Psychology)
- Description: As the divorce rate consistently rises, the occurrence of single parent families are becoming increasingly prevalent. Despite the marked increase in single custodial parents, research on this population (and more importantly, into the positive aspects such as their subjective well-being) has been neglected. Over the past three decades, psychologists have shifted the emphasis of their research from examining demographic and pathogenic factors to a positive psychology framework focusing on personality and resilience. The general aim of this study was to explore and describe the subjective wellbeing, including satisfaction with life and general happiness, of divorced, single custodial parents. In addition, this study aimed to identify potential patterns among the aspects of subjective well-being investigated and aimed to explore the relationships between these patterns. Thirty-five participants were included for participation in this study by means of non-probability, purposive sampling. The research measures included a biographical questionnaire, the Satisfaction with Life Scale (SWLS) and Affectometer-2 Scale (AFM-2). The data were analysed by the researcher and an independent statistician in terms of descriptive statistics and cluster analysis, or according to content analysis. This reflects a triangulation data collection and analysis method. Key findings included the following: The results of the SWLS indicated that the majority of participants reported being slightly dissatisfied with their lives. The results of the AFM-2 indicated that the participants generally had high levels of positive affect, and low levels of negative affect. However, the participants’ overall levels of happiness were still relatively low. A four cluster solution was obtained, with the clusters being significantly different from each other on all input variables. The first cluster experienced high levels of positive affect, low levels of negative affect, and high levels of overall happiness. The second cluster experienced predominantly slight dissatisfaction with their lives, high levels of positive affect, low levels of negative affect, and slightly low levels of overall happiness. The third cluster reported mostly dissatisfaction with their lives, low levels of positive affect, high levels of negative affect, and very low levels of overall happiness. The fourth cluster experienced predominantly slight satisfaction with xi life, slightly high levels of positive affect, neutral levels of negative affect, and low levels of overall happiness. It appeared that clusters containing participants who were satisfied with their jobs, were involved in a personal relationship and who participated in leisure activities, all experienced higher levels of subjective well-being. Overall, this study emphasises the value of and the need for South African research on the subjective wellbeing of divorced, single custodial parents.
- Full Text:
- Date Issued: 2005
Hijacking feminism: representations of the new woman in South African television advertising practice
- Authors: Klokow, Nicole Ann
- Date: 2005
- Subjects: Feminism and mass media -- South Africa , Television advertising -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8372 , http://hdl.handle.net/10948/381 , Feminism and mass media -- South Africa , Television advertising -- South Africa
- Description: This study examines the extent to which feminism has been appropriated by the consumer culture. As the relationship between consumerism and patriarchy continues to dominate global economic and social practices, this appropriation points to a denial of the social and political importance of the feminist movement. An acknowledgement of our own complicity in the perpetuation of a sexist, racist and classist ideology – along with an understanding of the complicity of the media – is crucial in explaining relations of domination within our society (Thompson 1990). A study of television advertising practice allows us to “explore meaning as a social product, enmeshed in webs of power” (Jordan and Wheedon 1995:543). Consumer ‘freedom’ is the compulsory freedom (Slater 1997), as we buy as many symbols as products. This study shows that for all the ‘strides’ feminism has made, media images of women are largely traditional, prescriptive (although an ironic distance is often implied) or overtly sexualised. Feminism is never mentioned, as women’s gains are presented as ahistorical in a ‘post-feminist’ world. Third wave feminism is an attempt to embrace all feminisms and feminists, working to inject some substance and truth behind advertising’s feminist veneer.
- Full Text:
- Date Issued: 2005
- Authors: Klokow, Nicole Ann
- Date: 2005
- Subjects: Feminism and mass media -- South Africa , Television advertising -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8372 , http://hdl.handle.net/10948/381 , Feminism and mass media -- South Africa , Television advertising -- South Africa
- Description: This study examines the extent to which feminism has been appropriated by the consumer culture. As the relationship between consumerism and patriarchy continues to dominate global economic and social practices, this appropriation points to a denial of the social and political importance of the feminist movement. An acknowledgement of our own complicity in the perpetuation of a sexist, racist and classist ideology – along with an understanding of the complicity of the media – is crucial in explaining relations of domination within our society (Thompson 1990). A study of television advertising practice allows us to “explore meaning as a social product, enmeshed in webs of power” (Jordan and Wheedon 1995:543). Consumer ‘freedom’ is the compulsory freedom (Slater 1997), as we buy as many symbols as products. This study shows that for all the ‘strides’ feminism has made, media images of women are largely traditional, prescriptive (although an ironic distance is often implied) or overtly sexualised. Feminism is never mentioned, as women’s gains are presented as ahistorical in a ‘post-feminist’ world. Third wave feminism is an attempt to embrace all feminisms and feminists, working to inject some substance and truth behind advertising’s feminist veneer.
- Full Text:
- Date Issued: 2005
An investigation into the antibacterial activities of medicinial plants traditionally used in the Eastern Cape to treat secondary skin infections associated with burn wounds
- Authors: Weideman, Liezel
- Date: 2005
- Subjects: Materia medica, Vegetable -- South Africa -- Eastern Cape , Burns and scalds -- Alternative treatment , Skin -- Infections
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10116 , http://hdl.handle.net/10948/172 , Materia medica, Vegetable -- South Africa -- Eastern Cape , Burns and scalds -- Alternative treatment , Skin -- Infections
- Description: Traditional medicine has a long history of being used for treating various ailments ranging in severity. Although traditional medicine has typically been the health care for the poorest levels of society, there is a worldwide growth in popularity. The growing popularity of traditional medicine, termed the green boom, may be ascribed to people taking a more holistic approach to maintain their health. Traditional medicine is widely used on a regular basis by 70% of South Africans. Various indigenous medicinal plants are used for the preparation of traditional herbal medicine. These plants are mostly indigenous to the regions were it is used. In this study four medicinal plants (Bulbine frutescens, Leonotis leounurus, Melianthus major & Zantedecshia aethiopica) that are traditionally used in the Eastern Cape region for treating burn wound infections, were collected for investigation. The in vitro antibacterial activity of these plants was tested against different bacterial strains of eight different bacteria. The bacteria used in this investigation included bacterial strains of four Gram-positive bacteria, S. aureus, methicillin-resistant S. aureus (MRSA), E. feacalis, S. pyogenes and four Gramnegative bacteria, P. aeruginosa, A. baumanii, K. pneumoniae and P. mirabilis. Traditional preparations as well as three different extracts (methanol, aqueous & acetone) of the plants were used for in vitro antibacterial activity testing. The microtitre plate assay and agar dilution assay were used for determining the antibacterial activity of the traditional preparations and plant extracts against the different bacterial strains. In the microtitre plate assay the antibacterial activity was tested using the bacterial growth indicator, INT and a microtitre plate spectrophotometer to determine the minimal inhibitory concentrations of the plant extracts and traditional preparations. The microtitre plate assay was used for testing the antibacterial activity of the plants against the bacterial strains of five bacteria, S. aureus, MRSA, P. aeruginosa, A. baumanii and K. pneumoniae. The bacterial strains of the three bacteria, S. pyogenes, E. feacalis and P. mirabilis were not compatible with the microtitre plate assay using INT and spectrophotometric readings to determine bacterial inhibition. Therefore the agar dilution assay were used as an alternative method for determining the MIC’s of the plant extracts against the bacterial strains of these bacteria. The initial plant extract concentration in the microtitre plate assay differed with the different plant extracts in the microtitre plate assay. Acetone followed by methanol extracted the highest plant extract concentrations with the different medicinal plants. M. major followed by L. leonurus produced the highest plant extract concentrations following extraction with the different extraction solvents. Consequently the acetone extract of M. major had the highest plant extract concentration before serial dilution in the microtitre plate assay. Uniform plant extract concentrations were tested in the agar dilution assay. The methanol extract followed by the acetone extract of the plants gave the highest antibacterial activity against the different bacterial strains. The extracts of M. major followed by L. leonurus inhibited the highest number of bacterial strains in the microtitre plate assay and the extracts of B. frutescens inhibited the lowest number of bacterial strains. The acetone and methanol extracts of M. major were the only extracts that displayed antibacterial activity in the agar dilution assay. The bacterial strains of P. mirabilis were the only bacteria that were inhibited using this method. The bacterial strains of S. pyogenes and E. feacalis were not inhibited at any of the plant extract concentrations in the agar dilution assay.
- Full Text:
- Date Issued: 2005
- Authors: Weideman, Liezel
- Date: 2005
- Subjects: Materia medica, Vegetable -- South Africa -- Eastern Cape , Burns and scalds -- Alternative treatment , Skin -- Infections
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10116 , http://hdl.handle.net/10948/172 , Materia medica, Vegetable -- South Africa -- Eastern Cape , Burns and scalds -- Alternative treatment , Skin -- Infections
- Description: Traditional medicine has a long history of being used for treating various ailments ranging in severity. Although traditional medicine has typically been the health care for the poorest levels of society, there is a worldwide growth in popularity. The growing popularity of traditional medicine, termed the green boom, may be ascribed to people taking a more holistic approach to maintain their health. Traditional medicine is widely used on a regular basis by 70% of South Africans. Various indigenous medicinal plants are used for the preparation of traditional herbal medicine. These plants are mostly indigenous to the regions were it is used. In this study four medicinal plants (Bulbine frutescens, Leonotis leounurus, Melianthus major & Zantedecshia aethiopica) that are traditionally used in the Eastern Cape region for treating burn wound infections, were collected for investigation. The in vitro antibacterial activity of these plants was tested against different bacterial strains of eight different bacteria. The bacteria used in this investigation included bacterial strains of four Gram-positive bacteria, S. aureus, methicillin-resistant S. aureus (MRSA), E. feacalis, S. pyogenes and four Gramnegative bacteria, P. aeruginosa, A. baumanii, K. pneumoniae and P. mirabilis. Traditional preparations as well as three different extracts (methanol, aqueous & acetone) of the plants were used for in vitro antibacterial activity testing. The microtitre plate assay and agar dilution assay were used for determining the antibacterial activity of the traditional preparations and plant extracts against the different bacterial strains. In the microtitre plate assay the antibacterial activity was tested using the bacterial growth indicator, INT and a microtitre plate spectrophotometer to determine the minimal inhibitory concentrations of the plant extracts and traditional preparations. The microtitre plate assay was used for testing the antibacterial activity of the plants against the bacterial strains of five bacteria, S. aureus, MRSA, P. aeruginosa, A. baumanii and K. pneumoniae. The bacterial strains of the three bacteria, S. pyogenes, E. feacalis and P. mirabilis were not compatible with the microtitre plate assay using INT and spectrophotometric readings to determine bacterial inhibition. Therefore the agar dilution assay were used as an alternative method for determining the MIC’s of the plant extracts against the bacterial strains of these bacteria. The initial plant extract concentration in the microtitre plate assay differed with the different plant extracts in the microtitre plate assay. Acetone followed by methanol extracted the highest plant extract concentrations with the different medicinal plants. M. major followed by L. leonurus produced the highest plant extract concentrations following extraction with the different extraction solvents. Consequently the acetone extract of M. major had the highest plant extract concentration before serial dilution in the microtitre plate assay. Uniform plant extract concentrations were tested in the agar dilution assay. The methanol extract followed by the acetone extract of the plants gave the highest antibacterial activity against the different bacterial strains. The extracts of M. major followed by L. leonurus inhibited the highest number of bacterial strains in the microtitre plate assay and the extracts of B. frutescens inhibited the lowest number of bacterial strains. The acetone and methanol extracts of M. major were the only extracts that displayed antibacterial activity in the agar dilution assay. The bacterial strains of P. mirabilis were the only bacteria that were inhibited using this method. The bacterial strains of S. pyogenes and E. feacalis were not inhibited at any of the plant extract concentrations in the agar dilution assay.
- Full Text:
- Date Issued: 2005
Metalorganic vapour phase epitaxial growth and characterisation of Sb-based semiconductors
- Authors: Vankova, Viera
- Date: 2005
- Subjects: Compound semiconductors , Epitaxy , Organometallic compounds , Metal organic chemical vapor deposition
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10548 , http://hdl.handle.net/10948/d1019678
- Description: This study focuses on the growth and characterization of epitaxial InAs and InAs1-xSbx. Layers are grown on InAs, GaAs and GaSb substrates by metalorganic vapour phase epitaxy, using trimethylindium, trimethylantimony and arsine as precursors. The growth parameters (V/III ratio, Sb vapour phase compositions) are varied in the temperature range from 500 ºC to 700 ºC, in order to study the influence of these parameters on the structural, optical and electrical properties of the materials. The layers were assessed by X-ray diffraction, electron and optical microscopy, photoluminescence and Hall measurements. Furthermore, the influence of hydrogenation and annealing on the electrical and optical properties of GaSb was investigated. It is shown that the growth temperature and the V/III ratio play a vital role in the resulting surface morphology of homoepitaxial and heteroepitaxial InAs layers. Growth at low temperatures is found to promote three-dimensional growth in both cases, with improvements in the surface morphologies observed for higher growth temperatures. All the investigated epilayers are n-type. It is shown that the electrical properties of heteroepitaxial InAs epilayers are complicated by a competition between bulk conduction and conduction due to a surface accumulation and an interface layer. The low temperature photoluminescence spectra of homoepitaxial InAs are dominated by two transitions. These are identified as band-to-band/excitonic and donor-acceptor recombination. The incorporation efficiency of antimony (Sb) into InAs1-xSbx is dependent on the growth temperature and the V/III ratio. Under the growth conditions used in this study, the incorporation efficiency of Sb is controlled by the thermal stability of the two constituent binaries (i.e. InAs and InSb). Changes in the low temperature photoluminescence spectra are detected with increasing x. From temperature and laser power dependent measurements, the highest energy line is attributed to band-to-band/excitonic recombination, while the peak appearing approximately 15 meV below this line is assigned to donor-acceptor recombination. The origin of an additional “moving” peak observed for higher Sb mole fraction x is tentatively attributed to quasi-donor-acceptor-recombination, arising from increased impurity/defect concentrations and a higher compensation ratio in the material. However, the unusual behaviour of this peak may also be ascribed to the presence of some degree of ordering in InAsSb. The exposure of a semiconductor to a hydrogen plasma usually leads to the passivation of shallow and deep centres, thereby removing their electrical and optical activity. In this study, the passivation and thermal stability of the native acceptor in p-type GaSb is also investigated. It is shown that this acceptor can be passivated, where after improvements in the electrical and optical properties of GaSb are observed. Upon annealing the passivated samples above 300 °C, the acceptor is reactivated.
- Full Text:
- Date Issued: 2005
- Authors: Vankova, Viera
- Date: 2005
- Subjects: Compound semiconductors , Epitaxy , Organometallic compounds , Metal organic chemical vapor deposition
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10548 , http://hdl.handle.net/10948/d1019678
- Description: This study focuses on the growth and characterization of epitaxial InAs and InAs1-xSbx. Layers are grown on InAs, GaAs and GaSb substrates by metalorganic vapour phase epitaxy, using trimethylindium, trimethylantimony and arsine as precursors. The growth parameters (V/III ratio, Sb vapour phase compositions) are varied in the temperature range from 500 ºC to 700 ºC, in order to study the influence of these parameters on the structural, optical and electrical properties of the materials. The layers were assessed by X-ray diffraction, electron and optical microscopy, photoluminescence and Hall measurements. Furthermore, the influence of hydrogenation and annealing on the electrical and optical properties of GaSb was investigated. It is shown that the growth temperature and the V/III ratio play a vital role in the resulting surface morphology of homoepitaxial and heteroepitaxial InAs layers. Growth at low temperatures is found to promote three-dimensional growth in both cases, with improvements in the surface morphologies observed for higher growth temperatures. All the investigated epilayers are n-type. It is shown that the electrical properties of heteroepitaxial InAs epilayers are complicated by a competition between bulk conduction and conduction due to a surface accumulation and an interface layer. The low temperature photoluminescence spectra of homoepitaxial InAs are dominated by two transitions. These are identified as band-to-band/excitonic and donor-acceptor recombination. The incorporation efficiency of antimony (Sb) into InAs1-xSbx is dependent on the growth temperature and the V/III ratio. Under the growth conditions used in this study, the incorporation efficiency of Sb is controlled by the thermal stability of the two constituent binaries (i.e. InAs and InSb). Changes in the low temperature photoluminescence spectra are detected with increasing x. From temperature and laser power dependent measurements, the highest energy line is attributed to band-to-band/excitonic recombination, while the peak appearing approximately 15 meV below this line is assigned to donor-acceptor recombination. The origin of an additional “moving” peak observed for higher Sb mole fraction x is tentatively attributed to quasi-donor-acceptor-recombination, arising from increased impurity/defect concentrations and a higher compensation ratio in the material. However, the unusual behaviour of this peak may also be ascribed to the presence of some degree of ordering in InAsSb. The exposure of a semiconductor to a hydrogen plasma usually leads to the passivation of shallow and deep centres, thereby removing their electrical and optical activity. In this study, the passivation and thermal stability of the native acceptor in p-type GaSb is also investigated. It is shown that this acceptor can be passivated, where after improvements in the electrical and optical properties of GaSb are observed. Upon annealing the passivated samples above 300 °C, the acceptor is reactivated.
- Full Text:
- Date Issued: 2005