Thermal pretreatment of diamond wire sawn multi-crystalline silicon wafers for wet acid texturization of solar cells

Abstract

Diamond wire sawn (DWS) multi-crystalline (mc) silicon wafers for solar cells are known to be difficult to texturize with the conventional wet acidic etching technology. Thermal annealing as pretreatment for wet acid texturization of the DWS mc-Si wafers has been studied. Improvement in morphology and reduction of the light reflectivity of the texture has been obtained with the pretreatment. Solar cells fabricated with the pre-treated DWS mc-Si wafers have been found to yield an ∼0.15% absolute efficiency gain in average, as compared with the solar cells fabricated in the same line with the same batch of wafers without the pretreatment. The thermal pretreatment was found to crystallize the amorphous surface layers on DWS mc-Si wafers. This is believed to be the reason for the above improvement. The present thermal pretreatment provides a promising low cost technology for texturization of DWS mc-Si wafers in photovoltaic industry.