Modeling of the grain boundary potential for poly-Si (solar cells)

New relations for the polysilicon grain boundary (GB) potential barrier height (V/sub g/) for both the dark and light cases are developed. The dependencies of electron lifetime ( tau ), mobility ( mu ), and diffusion length (L) on V/sub g/, depth, illumination level, and grain size are discussed. It is shown that V/sub g/ increases with depth under solar illumination, whereas the transport parameters decrease drastically. These results also show that under high-level illumination, V/sub g/ is reduced and the minority transport parameters are improved significantly, with a flatband condition (V/sub g/=0) appearing under certain conditions.<>