Characterisation of InAs-based epilayers by FTIR spectroscopy
- Authors: Baisitse, Tshepiso Revonia
- Date: 2007
- Subjects: Fourier transform infrared spectroscopy , Gallium arsenide semiconductors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10534 , http://hdl.handle.net/10948/474 , Fourier transform infrared spectroscopy , Gallium arsenide semiconductors
- Description: This study focuses on the characterization of InAs and InAs1-xSbx epitaxial layers by infrared reflectance and transmittance spectroscopy and Hall measurements. Reflectance measurements were performed in order to obtain the dielectric parameters and to extract from these information about the electrical properties (mobility and carrier concentration) of this important III-V material system. The transmittance measurements were used to determine the bandgap of InAsSb. Infrared reflectivity and transmittance measurements were performed in the wavelength range 200 – 2000 cm-1 on InAs and InAsSb layers grown on three types of substrates. A classical two oscillator model that takes into account both the free carriers and the lattice, was used to analyse the reflectance data using the BMDP® computer curve fitting software. The dielectric parameters and the electrical properties (carrier concentration and mobility) were extracted from the simulations. Due to the low free carrier concentration in the epitaxial structures, the plasma resonance frequency (ωp) values obtained from the simulations of reflectance spectra measured above 200 cm-1, were in the order of 20-30 cm-1. These low values were confirmed by direct measurements of ωp in reflectance spectra obtained in the range 15-200 cm-1. The simulated carrier concentration and mobility values determined optically were compared to the values determined by Hall measurements at room temperature and previously reported values by other researchers. The simulated values obtained were in reasonable agreement with the Hall values. The simulated and measured carrier concentrations obtained for InAs layers were significantly higher than the intrinsic carrier concentration for InAs at room temperature, indicating notable concentrations of donors resulting from the growth process.
- Full Text:
- Date Issued: 2007
- Authors: Baisitse, Tshepiso Revonia
- Date: 2007
- Subjects: Fourier transform infrared spectroscopy , Gallium arsenide semiconductors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10534 , http://hdl.handle.net/10948/474 , Fourier transform infrared spectroscopy , Gallium arsenide semiconductors
- Description: This study focuses on the characterization of InAs and InAs1-xSbx epitaxial layers by infrared reflectance and transmittance spectroscopy and Hall measurements. Reflectance measurements were performed in order to obtain the dielectric parameters and to extract from these information about the electrical properties (mobility and carrier concentration) of this important III-V material system. The transmittance measurements were used to determine the bandgap of InAsSb. Infrared reflectivity and transmittance measurements were performed in the wavelength range 200 – 2000 cm-1 on InAs and InAsSb layers grown on three types of substrates. A classical two oscillator model that takes into account both the free carriers and the lattice, was used to analyse the reflectance data using the BMDP® computer curve fitting software. The dielectric parameters and the electrical properties (carrier concentration and mobility) were extracted from the simulations. Due to the low free carrier concentration in the epitaxial structures, the plasma resonance frequency (ωp) values obtained from the simulations of reflectance spectra measured above 200 cm-1, were in the order of 20-30 cm-1. These low values were confirmed by direct measurements of ωp in reflectance spectra obtained in the range 15-200 cm-1. The simulated carrier concentration and mobility values determined optically were compared to the values determined by Hall measurements at room temperature and previously reported values by other researchers. The simulated values obtained were in reasonable agreement with the Hall values. The simulated and measured carrier concentrations obtained for InAs layers were significantly higher than the intrinsic carrier concentration for InAs at room temperature, indicating notable concentrations of donors resulting from the growth process.
- Full Text:
- Date Issued: 2007
A methodology for measuring and monitoring IT risk
- Authors: Tansley, Natalie Vanessa
- Date: 2007
- Subjects: Electronic data processing departments -- Security measures , Business -- Data processing -- Security measures , Information resources management , Information technology -- Security measures
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9781 , http://hdl.handle.net/10948/772 , Electronic data processing departments -- Security measures , Business -- Data processing -- Security measures , Information resources management , Information technology -- Security measures
- Description: The primary objective of the research is to develop a methodology for monitoring and measuring IT risks, strictly focusing on internal controls. The research delivers a methodology whereby an organization can measure its system of internal controls, providing assurance that the risks are at an acceptable level. To achieve the primary objective a number of secondary objectives were addressed: What are the drivers forcing organizations to better corporate governance in managing risk? What is IT risk management, specifically focusing on operational risk. What is internal control and specifically focusing on COSO’s internal control process. Investigation of measurement methods, such as, Balance Scorecards, Critical Success Factors, Maturity Models, Key Performance Indicators and Key Goal Indicators. Investigation of various frameworks such as CobiT, COSO and ISO 17799, ITIL and BS 7799 as to how they manage IT risk relating to internal control.
- Full Text:
- Date Issued: 2007
- Authors: Tansley, Natalie Vanessa
- Date: 2007
- Subjects: Electronic data processing departments -- Security measures , Business -- Data processing -- Security measures , Information resources management , Information technology -- Security measures
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9781 , http://hdl.handle.net/10948/772 , Electronic data processing departments -- Security measures , Business -- Data processing -- Security measures , Information resources management , Information technology -- Security measures
- Description: The primary objective of the research is to develop a methodology for monitoring and measuring IT risks, strictly focusing on internal controls. The research delivers a methodology whereby an organization can measure its system of internal controls, providing assurance that the risks are at an acceptable level. To achieve the primary objective a number of secondary objectives were addressed: What are the drivers forcing organizations to better corporate governance in managing risk? What is IT risk management, specifically focusing on operational risk. What is internal control and specifically focusing on COSO’s internal control process. Investigation of measurement methods, such as, Balance Scorecards, Critical Success Factors, Maturity Models, Key Performance Indicators and Key Goal Indicators. Investigation of various frameworks such as CobiT, COSO and ISO 17799, ITIL and BS 7799 as to how they manage IT risk relating to internal control.
- Full Text:
- Date Issued: 2007
An investigation into the representation of women in South African Cosmopolitan Magazine advertisements of 2004
- Authors: Ranchod, Amisha
- Date: 2007
- Subjects: Women in mass media , Women in advertising -- Africa, Southern , Sex in advertising -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8405 , http://hdl.handle.net/10948/784 , Women in mass media , Women in advertising -- Africa, Southern , Sex in advertising -- Africa, Southern
- Description: This study investigates the representations of women in advertisements featured in South African Cosmopolitan magazine published in 2004 so as to critically analyse the stereotypes of women it presents, the institutional mechanisms behind this and its implications for gender ‘constructions’. By using a random cluster sample, 60 advertisements found in Cosmopolitan were analysed to examine the stereotypical portrayals of women within its imagery. In addition, survey questionnaires were distributed amongst female students to determine whether exposure to advertisements featured in Cosmopolitan magazines moulds their thoughts with regard to South African women today, as well as to analyse their attitudinal change before and after exposure to a number of advertisements. It was found that even though the majority of respondents claimed to be aware of the stereotypical representations of women found in the advertisements, and did not believe that these portrayals were a true reflection of South African women, various aspects of their lives continue to be affected by these representations in a number of ways. The findings of this study indicate that the trend found in previous studies – that stereotypical images of women prevail in the media – is evident in South Africa too. It was established that the ideologies of both patriarchy and capitalism work together in supporting the pervasiveness of negative, disempowering portrayals of women in Cosmopolitan advertisements. Stereotypical imagery of women serve as the site at which the ideologies of capitalism and patriarchy fuse, drawing on a common, shared notion of the objectified female to further their goals of maximisation of profits and male dominance respectively.
- Full Text:
- Date Issued: 2007
- Authors: Ranchod, Amisha
- Date: 2007
- Subjects: Women in mass media , Women in advertising -- Africa, Southern , Sex in advertising -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8405 , http://hdl.handle.net/10948/784 , Women in mass media , Women in advertising -- Africa, Southern , Sex in advertising -- Africa, Southern
- Description: This study investigates the representations of women in advertisements featured in South African Cosmopolitan magazine published in 2004 so as to critically analyse the stereotypes of women it presents, the institutional mechanisms behind this and its implications for gender ‘constructions’. By using a random cluster sample, 60 advertisements found in Cosmopolitan were analysed to examine the stereotypical portrayals of women within its imagery. In addition, survey questionnaires were distributed amongst female students to determine whether exposure to advertisements featured in Cosmopolitan magazines moulds their thoughts with regard to South African women today, as well as to analyse their attitudinal change before and after exposure to a number of advertisements. It was found that even though the majority of respondents claimed to be aware of the stereotypical representations of women found in the advertisements, and did not believe that these portrayals were a true reflection of South African women, various aspects of their lives continue to be affected by these representations in a number of ways. The findings of this study indicate that the trend found in previous studies – that stereotypical images of women prevail in the media – is evident in South Africa too. It was established that the ideologies of both patriarchy and capitalism work together in supporting the pervasiveness of negative, disempowering portrayals of women in Cosmopolitan advertisements. Stereotypical imagery of women serve as the site at which the ideologies of capitalism and patriarchy fuse, drawing on a common, shared notion of the objectified female to further their goals of maximisation of profits and male dominance respectively.
- Full Text:
- Date Issued: 2007
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