Microcrystalline silicon prepared with hot-wire CVD

Abstract

The properties of microcrystalline silicon prepared by hot-wire chemical vapor deposition at various substrate temperatures and process-gas mixtures have been investigated with a view to the application of the material in thin-film solar cells. It was found that high deposition temperatures and strong hydrogen dilution of the process gas have detrimental effects on the electronic performance of the material. It is proposed that under these preparation conditions, hydrogen etching and the thermal desorption of hydrogen lead to poor grain-boundary passivation. We conclude that optimum microcrystalline-silicon solar-cell material is not necessarily obtained with the largest grain sizes and apparent highest crystalline content, but rather by material prepared under conditions that yield a compact morphology with effective grain-boundary passivation.