Analysis of an enhanced photoresponse observed at subgrain boundaries in polysilicon solar cells

In an earlier study, an enhanced photoresponse was observed at dislocation subgrain boundaries in a polysilicon solar cell. The sub-grain boundaries were revealed by X-ray topography methods. The enhanced photoresponse was attributed to preferential diffusion along the subgrain boundaries relative to a distance significant with respect to the value of the minority-carrier diffusion length. Using a theoretical model of the carrier collection at the preferentially diffused boundaries, the wavelength dependence of the enhanced carrier collection is calculated. These results generally confirm the earlier experimentally derived model.