Dissertation (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (p.222-231).

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xii, 56 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 51-53).

Thesis (M.S.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2000. / [Square root of three] appears as a radical over 3. Includes bibliographical references (leaf 47).

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisors: Sanjay K. Banerjee and Gyeong S. Hwang. Vita. Includes bibliographical references.

Philosophiae Doctor - PhD / Nanocrystalline silicon (nc-Si:H) is an interesting type of silicon with superior electrical properties that are more stable compared to amorphous silicon (a-Si:H). Silicon nitride (SiNₓ) thin films are currently the dielectric widely applied in the microelectronics industry and are also effective antireflective and passivating layers for multicrystalline silicon solar cells. Research into the synthesis and characterization of nc-Si:H and SiNₓ thin films is vital from a renewable energy aspect. In this thesis we investigated the film growth mechanisms and the filament stability during the hot-wire chemical vapour deposition (HWCVD) of nc-Si:H and SiNₓ thin films. During the HWCVD of nc-Si:H, electron backscatter diffraction (EBSD) revealed that the tantalum (Ta) filament aged to consists of a recrystallized Ta-core with Ta-rich silicides at the hotter centre regions and Si-rich Ta-silicides at the cooler ends nearer to the electrical contacts. The growth of nc-Si:H by HWCVD is controlled by surface reactions before and beyond the transition from a-Si:H to nc-Si:H. During the transition, the diffusion of hydrogen (H) within the film is proposed to be the reaction controlling step. The deposition pressure influenced the structural, mechanical and optical properties of nc-Si:H films mostly when the film thickness is below 250 nm. The film stress, optical band gap, refractive index and crystalline volume fraction approached similar values at longer deposition times irrespective of the deposition pressure. Filament degradation occurred during the HWCVD of SiNₓ thin films from low total flow rate SiH₄ / ammonia (NH₃) / H₂ gas mixture. Similar to the HWCVD of nc-Si:H, the Ta-core recrystallized and silicides formed around the perimeter. However, Tanitrides formed within the filament bulk. The extent of nitride and silicide formation, porosity and cracks were all enhanced at the hotter centre regions, where filament failure eventually occurred. We also applied HWCVD to deposit transparent, low reflective and hydrogen containing SiNₓ thin films at total gas flow rates less than 31 sccm with NH₃ flow rates as low as 3 sccm. Fluctuations within the SiNₓ thin film growth rates were attributed to the depletion of growth species (Si, N, and H) from the ambient and their incorporation within the filament during its degradation.

M.Sc. (Physics) / Please refer to full text to view abstract

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<p> Substantial development of silicon-based technology is required to continue to improve product reliability and production yield of silicon-based IC devices. Defects play a key role in process technology and research is required into their properties and interactions with host and impurity atoms. Cavities formed by ion implantation of helium into a silicon substrate are known to be efficient gettering sites for mobile interstitials and metallic impurities. In addition, the existence of a buried void layer drastically reduces the unintentional parasitic transistor gain in power devices by introducing mid-gap energy levels in the substrate. Utilizing slow positron annihilation spectroscopy (PAS), void formation by implanted He+ at a dose of lxl016/cm2 and energy of 60 keV subsequently subjected to various annealing conditions, i.e. different temperatures, times, ramp rate and ambients, is reported. Quantitative measurement of cavity sizes shows that the annealing temperature largely influences helium out-diffusion from the implanted region. Consequently, different void evolution processes associated with specific annealing temperatures are found. Furthermore, larger voids are formed in oxygen ambient leading us to suggest that the supersaturation of interstitials enhances bubble migration and coalescence during the stage when a large fraction of He atoms remains in the cavities. </p> <p> In recent years, SiGe pseudomorphic alloys have become attractive for heterostructure devices due to their higher mobility, lower noise and lower power consumption, as compared with traditional Si devices. More importantly, SiGe is highly compatible with Si processing technologies. With the continuous improvement of SiGe technology, it has been coupled with complementary metal oxide semiconductor (CMOS) technology and has the potential to replace III-V compound semiconductor devices in the near future. However, many unknowns remain in this material system. The study of point defect injection during various thermal treatments is important in itself, and would also allow additional tools for the study of dopant diffusion in the material under different conditions. With preexistent voids in the buried substrate, we performed furnace wet oxidation on a Si0.98Geo.08 sample at 900 °C for half an hour. A small shrinkage of the voids, as compared to complete annihilation in the case of inert annealing, signifies vacancy injection during the oxidation process. Possible defect generation mechanisms and difference in growth rate enhancement in dry and wet oxidation are discussed. Based on a literature review of Si and SiGe oxidation, we suggest that stress relaxation and the Si replacement mechanism are responsible for the catalytic effect of the oxide growth and the change of point defect generation. </p> / Thesis / Master of Applied Science (MASc)