Crystallization behavior of electron-beam-evaporated amorphous silicon films on textured glass substrates by flash lamp annealing

Abstract

Flash lamp annealing (FLA) is one of the short-duration annealing methods suitable for the crystallization of micrometer-order-thick amorphous silicon (a-Si) films for thin-film polycrystalline silicon (poly-Si) solar cells. The crystallization of electron-beam- (EB-) evaporated a-Si films formed on flat glass substrates by FLA is known to take place through explosive crystallization (EC), by which laterally stretched large crystal grains are formed. In this study, we experimentally investigate the behavior of the FLA-induced crystallization of EB-evaporated a-Si films on glass substrates with intentionally roughed surfaces. When a-Si films on the textured glass substrates receive a FL pulse light consisting of sub-pulses with variable emission frequency, macroscopic stripe patterns with a constant width are observed on the poly-Si surface. This indicates the emergence of EC in EB-evaporated a-Si films also on textured glass substrates, similar to the case of a-Si films on flat substrates. Poly-Si films formed on textured glass substrates have smaller Si crystal grains in the vicinity of the Si/glass interface than the grains near the surface. Moreover, the lateral crystallization velocity of a-Si films on textured glass substrates is smaller compared to that on flat glass substrates. These indicate that the behavior of the EC of EB-evaporated a-Si films is affected by the surface morphology of glass substrates.