Two-dimensional LBIC and internal quantum efficiency investigations of porous silicon-based gettering procedure in multicrystalline silicon

In this work, a porous silicon-based gettering technique was applied to multicrystalline silicon (mc-Si) wafers. Porous silicon (PS) was formed by the stain-etching technique and was used as a sacrificial layer for efficient external purification technique. The gettering procedure consists of achieving a PS/mc-Si/PS structure that undergoes a heat treatment at 900 degrees C for 90 min in an infrared furnace under a N-2 ambient. After removing the PS layers, mc-Si solar cells were realized. The effect of the gettering procedure was evaluated by means of the laser beam-induced current (LBIC) mapping, the internal quantum efficiency (IQE) mapping and the dark current-voltage (I-V) characteristic. Consequently. LBIC and IQE images show an enhancement of the gettered sample as compared to a reference untreated one. The serial resistance and the shunt resistance carried out from the dark I-V curves confirm this gettering-related solar cell improvement. (C) 2008 Elsevier B.V. All rights reserved.