A transmission electron microscopic and energy-dispersive X-ray spectroscopic study was made of S diffusion in polycrystalline CdS/CdTe heterojunctions. It was found that grain boundaries significantly assisted S diffusion in the CdTe layer when the latter was grown in the absence of O. That is, the S diffused more easily along grain boundaries than through grains. However, grain boundaries did not enhance S diffusion in CdTe when it was grown in the presence of O. This difference was attributed to the formation of Cd-O bonds, at the grain boundaries, which resisted S diffusion.

Do Grain Boundaries Assist S Diffusion in Polycrystalline CdS/CdTe Heterojunctions? Y.Yan, D.Albin, M.M.Al-Jassim: Applied Physics Letters, 2001, 78[2], 171-3