Mechanism of low-temperature crystallization of amorphous silicon by atomic hydrogen anneal

Amorphous silicon (a-Si) films prepared by catalytic chemical vapor deposition method using SiH4 and H2 gas mixtures are crystallized at temperatures <350°C by annealing in atomic hydrogen, (atomic hydrogen anneal: AHA). Atomic hydrogen was generated by catalytic cracking reaction of H2 gas on a heated tungsten catalyzer. The crystalline fraction of a-Si film sample increased from 0% to several-tens% by AHA, and at the same time, the sample was etched with a rate of several-tens nm/min by AHA. Crystallization and etching by AHA depend on structural properties which are related to potential crystallinity in the initial a-Si film samples.