Novel Double Acidic Texturing Process for Saw-Damage-Free Kerfless Multicrystalline Silicon Wafers

Abstract

Since the kerfless wafer method for manufacturing multicrystalline silicon (mc-Si) wafers does not involve a sawing process, there occurs no saw damage on the surface, and the product is characterized by a flat surface morphology. These wafers cannot be effectively textured under the conditions of a conventional acidic etching solution with stability or efficiency because the surfaces are free of the surface damage caused by sawing. The texturing process developed in this article uses a conventional acidic etching solution without additives and a metal catalyst; the resulting process is a novel double acidic texturing (DAT) process capable of texturing using hydrofluoric acid (HF), HNO3, CH3COOH, and deionized water. The kerfless wafers treated with this novel texturing treatment had a weighted average reflectance (R-w) of 25.40 %, which is similar to 5.76% less than that of kerfless wafers textured under conventional acidic texturing conditions (R-w = similar to 31.16%). A solar cell manufactured with the new DAT process showed an enhanced short-circuit current density (+2.65mA center dot cm(-2)), fill factor (+3.87%), and efficiency (+2.18%) than those of a cell fabricated without using this novel double treatment.