Minority carrier lifetime in plasma-textured silicon wafers for solar cells

Abstract

In this work a comparison between plasma-induced defects by two different SF6 texturing techniques, reactive ion etching (RIE) and high-density plasma (HDP) is presented. It is found that without any defect-removal etching (DRE), the minority carrier lifetime is the highest for the HDP technique. After DRE, the minority carrier lifetime rises as high as 750 μs for both RIE- and HDP-textured wafers at an excess carrier density of 1×1015 cm-3. The measured lifetimes correspond to an implied one-sun open-circuit voltage of around 680 mV compared to about 640 mV before DRE for the HDP-textured wafers. FZ silicon 〈1 0 0〉 wafers were used in this study. We also noted that in the RIE process, the induced defect density was significantly lower for wafers etched at 300 K than those etched at 173 K.