Thesis (M.S.)--University of Alabama at Birmingham, 2009. / Title from PDF title page (viewed Jan. 21, 2010). Includes bibliographical references (p. 57-58) .

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 (Ph. D. in Interdisciplinary Materials Science)--Vanderbilt University, May 2008. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--University of Alabama at Birmingham, 2008. / Description based on contents viewed Feb. 11, 2009; title from PDF t.p. Includes bibliographical references (p. 49-50).

In this thesis, we are making a new approach to fabricate silicon on insulator (SOI). By replacing the buried silicon dioxide and the silicon handling wafer with silicon carbide through hydrophilic wafer bonding, we have achieved silicon on crystalline silicon carbide for the first time and silicon on polycrystalline silicon carbide substrates at 150 mm wafer size. The conditions for the wafer bonding are studied and the surface and bond interface are characterized. Stress free and interfacial defect free hybrid wafer bonding has been achieved. The thermally unfavourable interfacial oxide that originates from the hydrophilic treatment has been removed through high temperature annealing, denoted as Ox-away. Based on the experimental observations, a model to explain the dynamics of this process has been proposed. Ox-away together with spheroidization are found to be the responsible theories for the behaviour. The activation energy for this process is estimated as 6.4 eV. Wafer bonding of Si and polycrystalline SiC has been realised by an intermediate layer of amorphous Si. This layer recrystallizes to some extent during heat treatment. Electronic and thermal testing structures have been fabricated on the 150 mm silicon on polycrystalline silicon carbide hybrid substrate and on the SOI reference substrate. It is shown that our hybrid substrates have similar or improved electrical performance and 2.5 times better thermal conductivity than their SOI counterpart. 2D simulations together with the experimental measurements have been carried out to extract the thermal conductivity of polycrystalline silicon carbide as κpSiC = 2.7 WK-1cm-1. The realised Si-on-SiC hybrid wafer has been shown to be thermally and electrically superior to conventional SOI and opens up for hybrid integration of silicon and wide band gap material as SiC and GaN.

This work aims to study the pressure dependence of the thickness of the epitaxial silicon carbide SiC film growing from crystalline silicon Si due to the heterogeneous reaction with gaseous carbon monoxide CO.

No description available.

Tandem solar cells are potentially much more efficient than the silicon solar cells that currently dominate the market but require materials with different bandgaps. This thesis presents work on silicon nanocrystals (Si-NC) embedded in silicon carbide (SiC), which are expected to have a higher bandgap than bulk Si due to quantum confinement, with a view to using them in the top cell of a tandem cell. The strong photoluminescence (PL) of precursor films used to prepare Si-NC in SiC (Si-NC/SiC) was markedly reduced upon Si-NC formation due to simultaneous out-diffusion of hydrogen that passivated dangling bonds. This cannot be reversed by hydrogenation and leads to weak PL that is due to, and limited by, non-paramagnetic defects, with an estimated quantum yield of ≤5×10^-7. Optical interference was identified as a substantial artefact and a method proposed to account for this. Majority carrier transport was found to be Ohmic at all temperatures for a wide range of samples. Hydrogenation decreases dangling bond density and increases conductivity up to 1000 times. The temperature-dependence of conductivity is best described by a combination of extended-state and variable-range hopping transport where the former takes place in the Si nanoclusters. Furthermore, n-type background doping by nitrogen and/or oxygen was identified. In the course of developing processing steps for Si-NC-based tandem cells, a capping layer was developed to prevent oxidation of Si-NC/SiC, and diffusion of boron and phosphorus in nanocrystalline SiC was found to occur via grain boundaries with an activation energy of 5.3±0.4 eV and 4.4±0.7 eV, respectively. Tandem cells with a Si-NC/SiC top cell and bulk Si bottom cell were prepared that exhibited open-circuit voltages V_oc of 900 mV and short-circuit current densities of 0.85 mAcm^-2. Performance was limited by photocurrent collection in the top cell; however, the V_oc obtained demonstrates tandem cell functionality.