The substrate effects on kinetics and mechanism of solid-phase crystalization of amorphous silicon thin films

Abstract

The substrate effects on solid-phase crystallization of amorphous silicon (a-Si) films deposited by low-pressure chemical vapor deposition (LPCVD) using Si2H6 gas have been extensively investigated. The a-Si films were prepared on various substrates, such as thermally oxidized Si wafer (SiO2/Si), quartz and LPCVD-oxide, and annealed at 600 degrees C in an N-2 ambient for crystallization. The crystallization behavior was found to be strongly dependent on the substrate even though all the silicon films were deposited in amorphous phase. It was first observed that crystallization in a-Si films deposited on the SiO2/Si starts from the interface between the a-Si and the substrate, so called interface-induced crystallization, while random nucleation process dominates on the other substrates. The different kinetics and mechanism of solid-phase crystallization is attributed to the structural disorderness of a-Si films, which is strongly affected by the surface roughness of the substrates.