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 °C for 90 min in an infrared furnace under a N2 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.