Hybrid-phase growth in microcrystalline silicon thin films deposited by plasma enhanced chemical vapor deposition at low temperatures

摘要

Crystallographic studies on microcrystalline silicon (μc-Si) films, which were prepared by very-high-frequency plasma-enhanced chemical vapor deposition at a low temperature of 180℃, have been performed employing thickness evolutions of x-ray and electron diffraction measurements. The experimental results revealed that amorphous phase in μc-Si is transited to crystalline phase in solid phase in whole region from the top to the bottom, and the transition to the (220) orientation is dominantly found. These growth phenomena are interpreted in terms of a proposed model, i.e., the hybrid-phase growth model consisting of conventional vapor-phase growth at the surface plus the solid-phase crystallization occurring in the film. Moreover, the hybrid-phase growth, particularly solid-phase crystallization at low temperatures, is discussed in conjunction with the further results on the thickness evolutions associated with μc-Si films deposited on various underlayers or at substrate temperatures of 160-350℃, or at SiH_4 concentrations of 3%-5%.