Effect of Cu doping on polycrystalline CdTe prepared by close-spaced sublimation

It is well known that Cu plays a key role in the CdTe solar cell. In this study, the effect of Cu on the resistivity of polycrystalline CdTe films was investigated. CdTe films with various thicknesses were deposited by Close-Spaced Sublimation (CSS) and their Cu concentration was varied. Temperature-resistivity measurements were performed and activation energies were calculated to identify the various defect levels that control the resistivity of the CdTe film. The effect of the cadmium chloride heat treatment on the Cu doped samples was also studied. Although the addition of both Cu and CdCl2 heat treatment caused a reduction in resistivity, a compensating mechanism was observed for Cu doping.