Phase variation of amorphous-Si and poly-Si thin films with excimer laser irradiation

Excimer laser induced crystallization of Si thin films was studied by Raman spectroscopy and transmission electron microscopy. Single pulses of laser with various energies were irradiated on two types of starting materials to analyze complicated effects of the laser crystallization. For energies higher than a threshold value, an obvious difference in crystallization was found between starting materials of amorphous Si (a-Si) and laser-crystallized Si (lc-Si). Microcrystals were generated in the former but not in the latter, which is attributed to the presence of nuclei which remained deep within the Ic-Si him during the film melting. Phase variation of a-Si and degradation of lc-Si induced by small-energy irradiation were also demonstrated.