Ellipsometric study of thermal and laser annealed amorphous and microcrystalline silicon films

Spectroscopic ellipsometry measurements were used to characterize thermally and laser annealed μc-Si and a-Si films deposited with the rf glow discharge method. The films were modeled as multilayer structures to estimate the dielectric functions, composition and thickness of each layer. It was found that the μc-Si films recrystallize at an energy density above 200 mJ/cm2 of the KrF excimer laser, with a crystallinity fraction above 70%. The thickness of the recrystallized layer increases with the energy density but the crystallinity fraction is almost unchanged above the threshold energy density. Our results show that the laser recrystallized layer of μc-Si has a higher uniformity and crystalline fraction compared to laser annealed a-Si films. The film composition of laser annealed samples also favorably compares with that of thermally annealed μc-Si and a-Si films.