Crystallization of amorphous silicon films by a Nd:YAG laser and correlated surface morphology

Abstract

The phosphorous (P)-doped hydrogenated amorphous silicon (a-Si:H) thin films were crystallized by a frequency-doubled (λ=532 nm) Nd:YAG pulsed nanosecond laser with laser beam shaping system introduced by a fly-eye lens array. The correlations among crystallization, stress and microstructures with surface morphology during crystallization process can be determined. The increased crystalline fraction (XC) is realized by a considerable stress release. It is observed that the periodic two dimensional grid patterns with the period of about 15 μm are formed at laser energy density (EL) of 740 mJ/cm2 and are very sensitive to the energy density. Further increasing laser energy density to laser ablation can give rise to the irradiation damage on the film with poor crystalline quality and high surface roughness.