Purely Intrinsic Poly-Silicon Films by Hot Wire Chemical Vapor Deposition

摘要: Poly-silicon films have been prepared by hot-wire chemical vapor deposition (HWCVD) from hydrogen diluted silane gas at a low temperature (430 °C). The optical gap of the poly-silicon is 1.1 eV, though with higher absorption than c-Si. grains preferential orientation (220) perpendicular to substrate an average crystallite size 70 nm. crystalline volume fraction 95% complete coalescence grains. Large structures up 0.5 μm could be observed in AFM micrograph. activation energy (0.54 eV) and carrier concentration (10 11 cm −3 ) indicate fully intrinsic nature films. μτ product carriers 7.1×10 −7 2 V −1 whereas ambipolar diffusion length (L D 334 excellent photo-conductive properties are attributed (∼10 17 defect density. HWCVD showed very small dependence mobility, indicating negligible trapping grain boundaries. Preliminary n-i-p cells incorporating i-layer yielded 3.15 % efficiency.