Investigation of orientation, surface morphology, impurity concentration and reflectivity of the multi-crystalline silicon wafers

Abstract

Multi-crystalline silicon (mc-silicon) ingot was grown using the directional solidification (DS) method. The grown ingot was sliced, and the grain orientations, grain size, surface morphology, and impurities concentration in the wafers were studied. The XRD pattern of as-cut wafers exhibited the formation of a more number of (111) oriented plane in the grown ingot. The scanning electron microscopy images showed the formation of worm-like trenches after the chemical etching of the sliced wafers. FTIR spectra showed the higher carbon concentration on the top wafers and higher oxygen concentration at the bottom wafers. At the central wafer of the middle brick, the calculated carbon and interstitial oxygen concentration result exhibited 4.740 × 1016 and 1.369 × 1017 atoms/cm3, respectively. The impurity concentration of carbon and oxygen is validated with simulation results. The reflectivity spectra revealed low reflectivity for the wafers sliced from the central brick compared to the peripheral brick. The presence of very less impurity concentration and low reflectivity of the middle wafer in the central portion of the ingot enhances the light absorption, which is beneficial for photovoltaic energy generation.