THE SUBSTRATE EFFECTS ON KINETICS AND MECHANISM OF SOLID-PHASE CRYSTALLIZATION OF AMORPHOUS-SILICON THIN-FILMS

The substrate effects on solid-phase crystallization of amorphous sili con (a-Si) films deposited by low-pressure chemical vapor deposition ( LPCVD) using Si2H6 gas have been extensively investigated. The a-Si fi lms 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 th e silicon films were deposited in amorphous phase. It was first observ ed that crystallization in a-Si films deposited on the SiO2/Si starts from the interface between the a-Si and the substrate, so called inter face-induced crystallization, while random nucleation process dominate s on the other substrates. The different kinetics and mechanism of sol id-phase crystallization is attributed to the structural disorderness of a-Si films, which is strongly affected by the surface roughness of the substrates.