Boron diffusion into silicon crystal with SiN_x layer as a reaction barrier

摘要

A boron depletion layer is formed on a silicon substrate, due to the presence of a silicon oxide layer, in which the solubility of boron is higher than that in the silicon substrate. This silicon oxide layer is formed during the boron diffusion process employing the BBr_3 solution. To avoid the formation of this silicon oxide layer, a silicon nitride layer was used as a reaction barrier on the surface of the silicon substrate. A 500 thick SiN _x layer deposited by PECVD on the silicon substrate was found to prevent the formation of the silicon oxide and resulting boron depletion layer on the silicon substrate. The PC1D simulation suggests that preventing the formation of this boron depletion layer by using SiN_x as a reaction barrier can enhance the solar cell conversion efficiency by 0.9 in an absolute value.