Deposition and Properties of Silicon on Graphite Substrates

Abstract

Polycrystalline silicon has been deposited on low‐cost graphite substrates by the thermal decomposition of silane and thermal reduction of trichlorosilane with hydrogen in a gas flow system. The microstructures and crystallographic properties of deposited silicon were studied over a wide range of deposition conditions by metallographic and x‐ray techniques, respectively. The observed differences in the properties of silicon layers deposited by silane and trichlorosilane processes were attributed to the difference in the chemical reversibility of the reactions. The microstructure of silicon deposited by the trichlorosilane process was improved by the addition of hydrogen chloride to the reactant mixture. Solar cells were prepared from silicon layers deposited on graphite substrates by a one‐step process using silane or trichlorosilane and appropriate dopants, and AMO efficiencies of up to 1.5% were obtained.