Hydrogen concentration in chalcopyrite thin-film solar cells

A survey of the hydrogen concentration distribution in the various layers of chalcopyrite solar cells is presented. Depth profiles were measured by the nuclear reaction analysis method for the glass substrate, Moback contact, Cu(In, Ga)S2 or Cu(In, Ga)Se2 absorber, CdS buffer, and ZnO window layer. We find that hydrogen is present in all layers in concentrations exceeding the solubility of hydrogen in the corresponding crystalline bulk materials. This indicates that the deposition process and the polycrystallinity of the layers favor the uptake of hydrogen. The measured concentrations range from some 1018 H/cm3 in the absorber up to some 1021 H/cm3 in the CdS buffer layer. Effects of annealing at elevated temperatures are reported.