Crystallization of sputtered amorphous silicon induced by silver–copper alloy with high crystalline volumeratio

Silver–copper alloy-induced crystallization of sputtered a-Si has been studied. In this alloy, Cu acts as a catalyst to accelerate the crystallization, while Ag acts as a new kind of buffer layer, different from Al2O3 and Si3N4, to obtain well-crystallized poly-Si films with short annealing time and free of post-treatment for ohmic contact. When the Cu content is limited to below 30%, Ag can effectively slow down the diffusion of Cu into Si and decrease the Cu–silicide nuclei density to improve the crystalline volume ratio from 80% to over 90%. A 1:4 ratio of Cu to Ag yields the best result. The crystalline volume ratio and Hall mobility reach nearly 100% and 29.4 cm2/V s, respectively. This high quality poly-Si film demonstrates a promising application in solarcells.