The effects of CdCl2 on CdTe electrical properties using a new theory for grain-boundary conduction

We have further advanced the theory of in-plane electrical conduction across grain-boundaries, which now includes an analytical solution to a two-step thermally-assisted tunneling model. In addition, we have modified the onestep thermally-assisted tunneling model to approximate the effect of grain-boundary barrier height inhomogeneity. We use these models to study the effects of the vapor CdCl2 treatment on the grain-boundary electrical properties of the thin polycrystalline films, as processed for solar cells. Compared to untreated polycrystalline CdTe, we find that the vapor CdCl2 treatment increases the dark grain-boundary barrier height and near grain-boundary doping. Also, both cases show little barrier height inhomogeneity.