ZnTe:Cu film properties and their impact on CdS/CdTe devices

A back contact containing a sputtered ZnTe:Cu interface layer can produce high-performing thin-film CdS/CdTe photovoltaic devices. We have found that small changes in ZnTe:Cu sputtering target fabrication processes affect the properties of the ZnTe:Cu films, which affect the performance of the resulting devices. Different target manufacturing techniques were investigated to study changes in ZnTe:Cu film properties and how they impact device performance. Compositional, optical, and electrical properties of films made from different target recipes were studied. It was found that the amount of oxygen in the targets and films is strongly linked to changes in material properties, especially in band tailing and optical bandgap.