Grain structure of thin-film silicon by zone melting recrystallization on SiC base layer

Abstract

The grain structure of thin-film silicon layers obtained by chemical vapor deposition and zone melting recrystallization (ZMR) on SiC barrier layers, as developed for thin-film solar cells, have been investigated by electron backscatter diffraction (EBSD). The occurrence of subgrain boundaries was checked by defect etching.Twin boundaries form 1 to 100μm wide stripes, which are nearly parallel to the scan direction of ZMR. We find that stripe structure and the dominant grain orientations differ significantly from previously published ZMR layers grown on SiO2 surface. In a comprehensive model it is shown how the twinning structure and the dominant grain orientation can be related to the growth kinetics. The electronic activity of the defects was measured by electron beam induced current (EBiC). Contrary to other defects, the twin boundaries show no enhanced recombination. Therefore the found growth regime has potential advantages with respect of electronic properties of the layers.