Influence of different surface treatments on multicrystalline silicon wafers for defect characterization by LBIC

Abstract

In this paper, we investigate the influence of different chemical treatments on the surface of multicrystalline Silicon (mc-Si) wafers, for both revealing grain boundaries and intra-grain defects. Electrical characterization by light beam-induced current (LBIC) was also carried out after the treatments. Several pieces of ~2 × 2 cm2, from mc-Si wafers, were mechanically polished and chemically etched and subsequently metallized with gold (on both surfaces) by sputtering, using optimized deposition times for doing transparent electrodes suitable for LBIC mapping. The surface treatments are discussed in terms of their capabilities to reveal the crystal defects and to provide the best conditions for efficient LBIC signals directly on silicon substrates, in the absence of a p–n junction. The best surface treatments allowing both revealing crystallographic defects and permitting the measurement of highly contrasted LBIC maps is the KOH etching. A large number of intra-grain defects are clearly revealed, being their electrical activity sensitively higher than that of the grain boundaries.