Direct evidence for diffusion and electromigration of Cu in CuInSe2

Cu diffusion in chalcopyrite CuInSe2 was studied directly, using 64Cu as a radioactive tracer. For diffusion from a thin surface layer, the Cu diffusion coefficients at 380 and 430 °C, were found to vary from 10−8 to 10−9 cm2/s. In case of diffusion from a volume source at 400 °C, a value of 10−10 cm2/s was calculated from diffusion profiles. Electromigration of Cu was demonstrated, by applying a strong electric field to a sample and following the redistribution of 64Cu, that had been thermally diffused into the sample, prior to electric field application.