250 nm amorphous silicon thin films were crystallized by a 355 nm YAG picosecond pulsed laser

then the crystallized samples were investigated by metallurgical microscope、Raman spectrometer and Xray spectrometer. The results show that with increasing laser energy the width of completely molten zone and partially molten zone increases remarkably. In the energy range from 15 μJ to 860 μJ

neither characteristic peak of amorphous silicon nor characteristic peak of crystalline silicon appears in Raman spectra of the completely molten zones in all samples

while Raman spectra of the partially molten zone exhibit the sharp characteristic peak of crystalline silicon

it might be because that the energy flux density received by completely molten zone was so big that the most of the amorphous silicon in this region was evaporated. This assumption was further reconfirmed by EDS(energy dispersive spectrometer)analysis results

which shows that the composition of the completely molten zone are mainly silicide produced by reaction between glass and silicon

and its surface are covered by silicon dioxide layer.