Scanning probe force microscopy of III-V semiconductor structures
- Authors: Kameni Boumenou, Christian
- Date: 2017
- Subjects: Scanning probe microscopy -- South Africa Semiconductors -- Optical properties
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13992 , vital:27380
- Description: In this dissertation, cross-sectional potential imaging of GaAs-based homoepitaxial, heteroepitaxial and quantum well structures, all grown by atmospheric pressure Metal-organic Vapor Phase Epitaxy (MOVPE) is investigated. Kelvin probe force microscopy (KPFM), using amplitude modulation (AM) and frequency modulation (FM) modes in air and at room temperature, is used for the potential imaging. Studies performed on n-type GaAs homoepitaxial structures have shown two different potential profiles, related to the difference in electron density between the semi-insulating (SI) substrate and the epilayers. It is shown that the contact potential difference (CPD) between the tip and sample is higher on the semi-insulating substrate side than on the n-type epilayer side. This change in CPD across the interface has been explained by means of energy band diagrams indicating the relative Fermi level positions. In addition, it has also been found that the CPD across the interface increases with electron density. This result is in qualitative agreement with theory. In addition, as known from literature, even under ambient conditions FM mode KPFM provides better lateral resolution and more realistic CPD values than AM mode KPFM. Compared to the case of AM mode analysis, where the experimental CPD values were on average of the theoretical values, the CPD values from FM mode analysis are on average of the theoretical ones. Furthermore, by using FM mode, the transition across the interface is sharper and the surface potential flattens/saturates as expected when scanning sufficiently far away from the junction. The non-neutral space charge region of the sample with an electron density of for example, is as measured by FM-KPFM, whereas for AM-KPFM, the width is even more than and the potential profiles do not saturate. For the p-type GaAs homoepitaxial structures, FM mode measurements from a sample with a dopant density of are presented. As in the case of n-type GaAs,a similar potential profile showing two main domains has been obtained. However, unlike the case of type GaAs where the potential measured on the epilayer side is higher than that on the substrate side, the potential on the epilayer side of the junction is lower in this case due to the fact that the Fermi level of p-type GaAs is below that of the substrate.
- Full Text:
- Date Issued: 2017
- Authors: Kameni Boumenou, Christian
- Date: 2017
- Subjects: Scanning probe microscopy -- South Africa Semiconductors -- Optical properties
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13992 , vital:27380
- Description: In this dissertation, cross-sectional potential imaging of GaAs-based homoepitaxial, heteroepitaxial and quantum well structures, all grown by atmospheric pressure Metal-organic Vapor Phase Epitaxy (MOVPE) is investigated. Kelvin probe force microscopy (KPFM), using amplitude modulation (AM) and frequency modulation (FM) modes in air and at room temperature, is used for the potential imaging. Studies performed on n-type GaAs homoepitaxial structures have shown two different potential profiles, related to the difference in electron density between the semi-insulating (SI) substrate and the epilayers. It is shown that the contact potential difference (CPD) between the tip and sample is higher on the semi-insulating substrate side than on the n-type epilayer side. This change in CPD across the interface has been explained by means of energy band diagrams indicating the relative Fermi level positions. In addition, it has also been found that the CPD across the interface increases with electron density. This result is in qualitative agreement with theory. In addition, as known from literature, even under ambient conditions FM mode KPFM provides better lateral resolution and more realistic CPD values than AM mode KPFM. Compared to the case of AM mode analysis, where the experimental CPD values were on average of the theoretical values, the CPD values from FM mode analysis are on average of the theoretical ones. Furthermore, by using FM mode, the transition across the interface is sharper and the surface potential flattens/saturates as expected when scanning sufficiently far away from the junction. The non-neutral space charge region of the sample with an electron density of for example, is as measured by FM-KPFM, whereas for AM-KPFM, the width is even more than and the potential profiles do not saturate. For the p-type GaAs homoepitaxial structures, FM mode measurements from a sample with a dopant density of are presented. As in the case of n-type GaAs,a similar potential profile showing two main domains has been obtained. However, unlike the case of type GaAs where the potential measured on the epilayer side is higher than that on the substrate side, the potential on the epilayer side of the junction is lower in this case due to the fact that the Fermi level of p-type GaAs is below that of the substrate.
- Full Text:
- Date Issued: 2017
The use of lean tools to increase productivity and improve efficiency in Port Elizabeth Enforcement Audit
- Authors: Bantom, Phumeza Patience
- Date: 2011
- Subjects: Lean manufacturing , Quality control -- Auditing , Waste minimization , Auditing, Internal
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8645 , http://hdl.handle.net/10948/d1008159 , Lean manufacturing , Quality control -- Auditing , Waste minimization , Auditing, Internal
- Description: Lean philosophy is based on the continuous quest to improve the organisation‟s processes by creating a culture and operating principles which eliminate all non value adding activities within organisation„s processes. Manufacturing firms consider the adoption of the Lean tools as basic requirements for achieving World Class operational excellence or Best Practice. For some time, lean has been used by the manufacturing organizations. Most organizations understand that lean will help them survive global competition and stay in business. The objective of this study is to investigate how lean manufacturing tools can be used to improve efficiency and enhance the embedding of a continuous improvement culture in the South African Revenue Service Enforcement Audit Port Elizabeth. The activities that took place in Enforcement Audit Port Elizabeth from September 2010 until 31 October 2011 were observed. During the study, an introductory presentation by the researcher was made to Regional Enforcement Management and staff in general, the presentation was to introduce the study highlighting different Lean tools. Thereafter the Port Elizabeth audit staff members were engaged formally, using surveys to assess their underlying mindset and behaviour as well as informally, using unstructured interviews to solicit more information on activities taking place and the reasoning behind certain actions. The results of the survey and observations are analysed and interpreted.
- Full Text:
- Date Issued: 2011
- Authors: Bantom, Phumeza Patience
- Date: 2011
- Subjects: Lean manufacturing , Quality control -- Auditing , Waste minimization , Auditing, Internal
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8645 , http://hdl.handle.net/10948/d1008159 , Lean manufacturing , Quality control -- Auditing , Waste minimization , Auditing, Internal
- Description: Lean philosophy is based on the continuous quest to improve the organisation‟s processes by creating a culture and operating principles which eliminate all non value adding activities within organisation„s processes. Manufacturing firms consider the adoption of the Lean tools as basic requirements for achieving World Class operational excellence or Best Practice. For some time, lean has been used by the manufacturing organizations. Most organizations understand that lean will help them survive global competition and stay in business. The objective of this study is to investigate how lean manufacturing tools can be used to improve efficiency and enhance the embedding of a continuous improvement culture in the South African Revenue Service Enforcement Audit Port Elizabeth. The activities that took place in Enforcement Audit Port Elizabeth from September 2010 until 31 October 2011 were observed. During the study, an introductory presentation by the researcher was made to Regional Enforcement Management and staff in general, the presentation was to introduce the study highlighting different Lean tools. Thereafter the Port Elizabeth audit staff members were engaged formally, using surveys to assess their underlying mindset and behaviour as well as informally, using unstructured interviews to solicit more information on activities taking place and the reasoning behind certain actions. The results of the survey and observations are analysed and interpreted.
- Full Text:
- Date Issued: 2011
The application of section 197 of the Labour Relations Act in an outsourcing context
- Authors: Biggs, Lynn
- Date: 2008
- Subjects: South Africa. Labour Relations Act (1995) , Labor laws and legislation -- South Africa , Contracting out -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10193 , http://hdl.handle.net/10948/751 , South Africa. Labour Relations Act (1995) , Labor laws and legislation -- South Africa , Contracting out -- Law and legislation -- South Africa
- Description: Section 197 of the Labour Relations Act (LRA) in both its original form and in its current form caused much confusion and debate. Originally it was interpreted that section 197 allowed for the automatic transfer of employees in cases where there was a transfer of the whole or part of a business, trade or undertaking as a going concern. That meant that the contracts of employment transfer to the new owner and that the employees could not refuse to be transferred. Various judges were tasked with interpreting this section in its original form and thus different interpretations emerged with the Labour Appeal Court ultimately deciding in the NEHAWU v University of Cape Town matter that employers involved in the transfer can decide between them, not to transfer the employees. The LAC further held that “outsourcing” does not necessarily entail a transfer of a business. Section 197 was amended in 2002 and the effect of the provisions is that the old employer is not required to seek the consent of the employees before their contracts are transferred and that the employment contracts transfer automatically. However, the current section has also raised some difficulties especially relating to: when does a transfer of a business as a going concern take place; what constitutes a “business”; when is an entity part of a business, trade, undertaking or service? A more glaring controversy relates to whether section 197 applies to “second-generation contracting out or outsourcing”. All provisions of the LRA should be interpreted in the context to advance economic development, social justice, labour peace and democratisation of the workplace. One of the primary objects of the LRA is to give effect to and to regulate the fundamental rights of the Constitution of the Republic of South Africa, 1996. Thus section 197 is to be interpreted in light of the objectives of the LRA as well as to promote the spirit, purport and objects of the Bill of Rights. The common law and international law are both important sources of comparison. The common law allows employers who transfer businesses free to decide whether or not the transfer will include the employees of the transferor. International law, particularly the European Union and the United Kingdom, favour the approach that when an entity is transferred, it retains its identity after the transfer and the safeguarding of employee rights in the context of business transfers. European and English jurisprudence have shown that almost any combination of events can constitute a transfer of a business.
- Full Text:
- Date Issued: 2008
- Authors: Biggs, Lynn
- Date: 2008
- Subjects: South Africa. Labour Relations Act (1995) , Labor laws and legislation -- South Africa , Contracting out -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10193 , http://hdl.handle.net/10948/751 , South Africa. Labour Relations Act (1995) , Labor laws and legislation -- South Africa , Contracting out -- Law and legislation -- South Africa
- Description: Section 197 of the Labour Relations Act (LRA) in both its original form and in its current form caused much confusion and debate. Originally it was interpreted that section 197 allowed for the automatic transfer of employees in cases where there was a transfer of the whole or part of a business, trade or undertaking as a going concern. That meant that the contracts of employment transfer to the new owner and that the employees could not refuse to be transferred. Various judges were tasked with interpreting this section in its original form and thus different interpretations emerged with the Labour Appeal Court ultimately deciding in the NEHAWU v University of Cape Town matter that employers involved in the transfer can decide between them, not to transfer the employees. The LAC further held that “outsourcing” does not necessarily entail a transfer of a business. Section 197 was amended in 2002 and the effect of the provisions is that the old employer is not required to seek the consent of the employees before their contracts are transferred and that the employment contracts transfer automatically. However, the current section has also raised some difficulties especially relating to: when does a transfer of a business as a going concern take place; what constitutes a “business”; when is an entity part of a business, trade, undertaking or service? A more glaring controversy relates to whether section 197 applies to “second-generation contracting out or outsourcing”. All provisions of the LRA should be interpreted in the context to advance economic development, social justice, labour peace and democratisation of the workplace. One of the primary objects of the LRA is to give effect to and to regulate the fundamental rights of the Constitution of the Republic of South Africa, 1996. Thus section 197 is to be interpreted in light of the objectives of the LRA as well as to promote the spirit, purport and objects of the Bill of Rights. The common law and international law are both important sources of comparison. The common law allows employers who transfer businesses free to decide whether or not the transfer will include the employees of the transferor. International law, particularly the European Union and the United Kingdom, favour the approach that when an entity is transferred, it retains its identity after the transfer and the safeguarding of employee rights in the context of business transfers. European and English jurisprudence have shown that almost any combination of events can constitute a transfer of a business.
- Full Text:
- Date Issued: 2008
The tax implications of a private equity buy-out : a case study of the Brait-Shoprite buy-out
- Authors: Mawire, Patrick N
- Date: 2008
- Subjects: South African Revenue Service , Consolidation and merger of corporations -- Finance , Taxation -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:8959 , http://hdl.handle.net/10948/803 , South African Revenue Service , Consolidation and merger of corporations -- Finance , Taxation -- Law and legislation -- South Africa
- Description: This treatise examines the history of private equity as a context in which to understand its role in the economy and specifically, the background for the high profile leveraged buy-outs that have been entered into in the past year. The treatise then focuses specifically on the Brait-Shoprite buy-out, examining its structure and the tax implications. The treatise then reviews the reaction of the South African Revenue Authority (“SARS”) to the buy-out and evaluates whether it was the best approach that could have been taken under the circumstances. As a result of the research, the following conclusions have been reached: Private equity transactions Private equity transactions have a role to play in the business world despite the apprehensions of tax authorities. The perception that these transactions are tax driven as part of an avoidance scheme is not justified. Structure of the Shoprite buy-out transaction: The Shoprite buy-out transaction was structured to obtain deduction for interest. The transaction was also structured to utilise the relief provisions of Part II of Chapter II (Special Provisions Relating to Companies) of the Income Tax Act no.58 of 1962, as amended (“the Act”). The relief was for capital gains tax (“CGT”) on disposal of the Shoprite assets. Finally, the transaction was designed to allow the existing shareholders to exit their investments free of Secondary Tax on Companies (“STC”). The reaction of SARS to the Shoprite buy-out transaction Whereas SARS may have been justified in questioning the structure and its impact on fiscal revenue, the response in the form of withdrawing STC relief from amalgamation transactions in section 44 was not in the best interest of a stable tax system and the majority of tax payers who are not misusing or abusing loopholes in the income tax legislation. It may have been possible for SARS to attack the structure based on the General Anti-Avoidance Rule (GAAR) in part IIA of the Chapter III of the Act.
- Full Text:
- Date Issued: 2008
- Authors: Mawire, Patrick N
- Date: 2008
- Subjects: South African Revenue Service , Consolidation and merger of corporations -- Finance , Taxation -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:8959 , http://hdl.handle.net/10948/803 , South African Revenue Service , Consolidation and merger of corporations -- Finance , Taxation -- Law and legislation -- South Africa
- Description: This treatise examines the history of private equity as a context in which to understand its role in the economy and specifically, the background for the high profile leveraged buy-outs that have been entered into in the past year. The treatise then focuses specifically on the Brait-Shoprite buy-out, examining its structure and the tax implications. The treatise then reviews the reaction of the South African Revenue Authority (“SARS”) to the buy-out and evaluates whether it was the best approach that could have been taken under the circumstances. As a result of the research, the following conclusions have been reached: Private equity transactions Private equity transactions have a role to play in the business world despite the apprehensions of tax authorities. The perception that these transactions are tax driven as part of an avoidance scheme is not justified. Structure of the Shoprite buy-out transaction: The Shoprite buy-out transaction was structured to obtain deduction for interest. The transaction was also structured to utilise the relief provisions of Part II of Chapter II (Special Provisions Relating to Companies) of the Income Tax Act no.58 of 1962, as amended (“the Act”). The relief was for capital gains tax (“CGT”) on disposal of the Shoprite assets. Finally, the transaction was designed to allow the existing shareholders to exit their investments free of Secondary Tax on Companies (“STC”). The reaction of SARS to the Shoprite buy-out transaction Whereas SARS may have been justified in questioning the structure and its impact on fiscal revenue, the response in the form of withdrawing STC relief from amalgamation transactions in section 44 was not in the best interest of a stable tax system and the majority of tax payers who are not misusing or abusing loopholes in the income tax legislation. It may have been possible for SARS to attack the structure based on the General Anti-Avoidance Rule (GAAR) in part IIA of the Chapter III of the Act.
- Full Text:
- Date Issued: 2008
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