EBSD analysis of polysilicon films formed by aluminium induced crystallization of amorphous silicon

Among the methods for enlarging the grain size of polycrystalline silicon (poly-Si) thin films, aluminium induced crystallization (AIC) of amorphous silicon is considered to be a very promising approach. In the AIC process, a thin a-Si layer on top of an aluminium layer crystallizes at temperatures well below the eutectic temperature of the Al/Si system (Teu = 577 deg. C). By means of electron backscattering diffraction (EBSD), we have mainly studied the effect of the aluminium layer quality varying the deposition system on the grain size, the defects and the preferential crystallographic orientation. We have found a strong correlation between the mean grain size and the size distribution with the Al deposition system and the surface quality. Furthermore, we show for the first time that more than 50% of the surface of the AIC films grown on alumina substrates are (103) preferentially oriented, instead of the commonly observed (100) preferential orientation. This may have important consequences for epitaxial thickening of the AIC layer into polysilicon absorber layers for solar cells