Progress in the development of microcrystalline 3C-SiC, SiGeC and GeC thin films for solar cell applications

The research and development of microcrystalline 3C-SiC, SiGeC and GeC thin films for solar cell applications are presented. Hot wire CVD technique is employed to optimize the deposition parameters for achieving high quality /spl mu/c-3C-SiC thin films whose bandgap is 2.2 eV. Monomethylsilane and hydrogen are used as reactant gases for the deposition of /spl mu/c-SiC thin films. P and Al are used as dopants to successfully obtain n and p type /spl mu/c-3C-SiC thin films. Doped /spl mu/c-3C-SiC is very attractive for the potential window layer applications in Si thin film and Si heterojunction solar cells. Attempts to control the bandgap of /spl mu/c-3C-SiC are done by incorporating Ge into SiC. Of late, we have succeeded to prepare /spl mu/c-3C-SiGeC with a Ge content of 5%, which showed about 0.2 eV lower absorption spectra compared to that of 3C-SiC.