Structure and properties of silicon thin films deposited at low substrate temperatures

Silicon thin films were grown near the microcrystalline/amorphous boundary at substrate temperatures T-S = 35-200degreesC and dilutions [H-2]/[SiH4] = 25-167. The conductivity percolation threshold Occurred at crystallinity similar to60%, above the random composite threshold 33.3%, due to amorphous tissue coating crystalline grains and limiting the electronic transport. Higher content of hydrogen at lower T-S facilitates formation of ordered silicon phase even close to room temperature (the sample grown at 35degreesC had 30 at% of hydrogen and crystallinity similar to 60%), providing a technological window for deposition of silicon thin films on cheap polymer substrates with electronic properties Suitable for solar cells.