The polycrystalline silicon films were fabricated by Solid Phase Crystallization(SPC) of amorphous silicon deposited by low pressure chemical vapor deposition(LPCVD). The samples are deposited by using $Si_2H_6$ in the temperature range 460~520℃ and annealed at 600℃, and studied by optical transmittance, dark conductivity, X-ray diffraction, Raman scattering, and SEM. In this study, the deposition process is governed by the surface reaction controlled mechanism. For all deposition pressures the optical gap decreases as the deposition temperature increases, which indicates the disorder of the amorphous state is increased.
Hydrogenation increases both the optical gap and activation energy. After annealing for 32hrs, dark conductivity data shows all the samples have activation energy about 0.6eV, which indicates amorphous - polycrystalline transition. Structural analyses indicate that the maximum grain size is obtained at the substrate temperature of 500℃, where the nucleation rate is minimum due to the maximum structural disorder of the silicon network.
