Experimental study of aluminum-induced crystallization of amorphous silicon thin films

Abstract

This work was an experimental study of the aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) for the fabrication of polycrystalline silicon film. The a-Si film was deposited on silicon wafer by low pressure chemical vapor deposition (LPCVD) technique. Aluminum was sputtered on to the a-Si film at different thicknesses. The samples were annealed for 3 h at different temperatures from 250 to 550 °C. The annealed silicon films were analyzed with emphasis on their crystallinity and morphology. Results showed that in the presence of aluminum, a-Si film started crystallization at a temperature as low as 250 °C. However, high crystallization rate would be achieved only when the annealing was done at temperatures higher than 350 °C. For practical applications, this temperature might well be the lower limit in AIC method for crystallization of silicon. The thickness of aluminum film was found to play a critical role that dictated the extent of crystallization and the preferred orientation of the resulting polycrystalline thin film.