PULSED EXCIMER-LASER CRYSTALLIZATION OF EVAPORATED AMORPHOUS-SILICON FILMS - THE ROLE OF SIO2 UNDERLAYER THICKNESS

Amorphous Si (a-Si) films deposited by vacuum evaporation onto oxidize d Si substrates with different thicknesses of SiO2 underlayer were mel ted and crystallized using a XeCl laser beam. The energy densities of the beam F = 150 to 450 mJ/cm(2) were chosen according: to the results of calculations of the temperature evolution within the samples. A-Si films were irradiated by n = 1, 10, or 100 laser pulses. The samples were analyzed by X-ray diffraction (XRD), grazing incidence XRD (GI XR D)I transmission and scanning electron microscopy. The influence of th e underlying SiO2 thickness on the crystallization was studied. It was shown that the complete or near-complete melting of a-Si and higher t emperature gradients in the melted Si (depending on the SiO2 thickness ) are favourable conditions for Si crystallization. Overmnelting into the oxide resulted in a lower quality of Si film crystallinity.