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Cubic boron nitride (c-BN) has been in focus for several years due to its interesting properties. The possibility for large area chemical vapor deposition (CVD) is a requirement for the realization of these different properties in various applications. Unfortunately, there are at present severe problems in the CVD growth of c-BN. The purpose with this research project has been to theoretically investigate, using density functional theory (DFT) calculations, the possibility for a layer-by-layer CVD growth of c-BN.  The results, in addition with experimental work by Zhang et al.57,  indicate that plasma-enhanced atomic layer deposition (PEALD), using a BF3-H2-NH3-F2 pulse cycle and a diamond substrate, is a promising method for deposition of c-BN films. The gaseous species will decompose in the plasma and form BFx, H, NHx, and F species (x = 0, 1, 2, 3). The H and F radicals will uphold the cubic structure by completely hydrogenate, or fluorinate, the growing surface. Surface radical sites will appear during the growth process as a result of atomic H, or F, abstraction reactions. However, introduction of energy (e.g., ionic bombardment) is probably necessary to promote removal of H from the surface. The addition of NHx growth species (x = 0, 1, 2) to the B radical sites, and BFx growth species (x = 0, 1, 2) to N radical sites, will then result in a continuous growth of c-BN.

Currently the cost of solar grade silicon accounts for approximately one third of the total solar cell cost, therefore a new silicon refining process is being proposed with the goal of lowering the cost of producing solar grade silicon. In this new process, Si-Cu alloys were used as the silicon source. One to one molar ratio H2-HCl gas mixtures were used as transport agents to extract Si out from the Si-Cu alloy at about 300-700oC, with following reaction taking place: Si+3HCl(g)=HSiCl3(g)+H2(g) While at about 1000-1300oC, pure Si deposits onto a hot silicon rod according to: Si+3HCl(g)=HSiCl3(g)+H2(g) The role of the copper in the alloy was to trap impurities in the Si and catalyze the gas solid reaction. A study on determining the rate limiting step and impurity behavior was done. A possible silicon extraction reaction mechanism was also addressed.

Currently the cost of solar grade silicon accounts for approximately one third of the total solar cell cost, therefore a new silicon refining process is being proposed with the goal of lowering the cost of producing solar grade silicon. In this new process, Si-Cu alloys were used as the silicon source. One to one molar ratio H2-HCl gas mixtures were used as transport agents to extract Si out from the Si-Cu alloy at about 300-700oC, with following reaction taking place: Si+3HCl(g)=HSiCl3(g)+H2(g) While at about 1000-1300oC, pure Si deposits onto a hot silicon rod according to: Si+3HCl(g)=HSiCl3(g)+H2(g) The role of the copper in the alloy was to trap impurities in the Si and catalyze the gas solid reaction. A study on determining the rate limiting step and impurity behavior was done. A possible silicon extraction reaction mechanism was also addressed.

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