Technology and equipment design for high throughput low-cost Epi for PV and discrete power applications

The globally booming PV industry is constantly looking for new ways to cut the cost of a solar cell in order to get a more competitive cost per Watt. The most evident way to achieve that is to develop new solar cell designs using much less silicon thus providing lower cost of material. A number of solar cell concepts using silicon thin films have been developed and brought to the market in recent years. Most thin film solar cell designs feature a layer of silicon mounted on a low cost substrate made of glass, ceramics or low purity silicon. The critical issue is forming a quality silicon layer and keeping the process cost down at the same time. The use of Epitaxy allows to produce multi-layer structures with layers having various thickness and doping characteristics. Epitaxial technology carries a great potentilal for solar cell manufacturing, but with a standard epi deposition process the cost is too high and productivity is not high enough to make it feasible. Epiel has developed a method of making multy-layer structures using epitaxial deposition technique largely different from standard process used for IC manufacturing. Silicon is deposited on a substrate by mass transfer over a small gap from a solid source material, for instance Silicon wafer, in Hydrogen environment with minimum source gas flow or in still atmosphere. Samples produced in test runs on a prototype unit have very good layer quality even when deposited on a substrate with rough surface. The growth rate can be as high as 14 um/min allowing for high productivity, and gases consumption is very low. This makes the new technique an attractive alternative to existing thin film concepts. See RU Patent "Method of making semiconductor structures" at link.
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