Modeling of Surface Reflectance of Acid Textured Multicrystalline Silicon Wafer for Solar Cell Application

This paper deals with the theoretical modeling of surface reflectance of acid textured multicrystalline wafer used in the processing of solar cell to minimize the surface reflectivity and there by enhancing the efficiency of the cell without wasting the wafers and time in optimizing the texturization process for the development of high efficiency solar cell. In the present study, texturization of mc-Si has been carried out in acidic solution using different compositions of HF, HNO3 and H3PO4 at different temperatures and for varying etching time (45-195 s). The best results were obtained for wet acidic ice cooled solution of HF:HNO3:H3PO4 :: 10:1:5 when textured for 165 s. Attempts have been made to explain the reflectivity behavior of the textured surfaces of the mc-Si wafers on the basis of the scanning electron microscopic (SEM) micrographs and theoretical modeling of reflectivity assuming the textured surface as a part of a hemisphere. It was observed that the average experimental reflectivity decreases as the etching time increases from 45 s to 165 s and attains a minimum value of 18% for the etching time of 165 s. The experimental reflectivity curve for the etching time of 165 s matches very well with the calculated reflectivity curve for h/D ratio of 0.50 in the wavelength range of 7001050nm. These techniques are seems to be useful for large area industrial solar cell applications and the developed theoretical modeling software package may be suitably used for optimizing the texturization parameters of mc-Si wafers for achieving the minimal reflectance values for increasing the efficiency of solar cell.