Newly developed multicrystalline silicon wafer with diffusion length over 250 /spl mu/m

In this paper, we improved the quality of the silicon wafers which was important in the improvement in conversion efficiency of the photovoltaic system using multicrystalline silicon. Crystal grains were observed in the cross section of the multicrystalline silicon ingots obtained by the conventional casting method and the MUST (MUlti-STage solidification controlling) method. The wafer manufactured by the MUST method was observed by using EBIC. The average diffusion length of the wafer is over 250 /spl mu/m. When the cell was made from the wafer by MUST method, 18.3% of efficiency could be acquired in the cell. There was little degradation of current in grain boundary of the wafer manufactured using the MUST method.