Sputtered HRT layers for CdTe solar cells

This work focuses on demonstrating the suitability of various high resistivity transparent (HRT) layers prepared by magnetron sputtering for sputtered CdS/CdTe cells. HRT buffer layers added between the transparent conducting oxide (TCO), and the CdS layer are important for reducing the effects of non-uniformities and shunts in large-area thin-film devices. CdS/CdTe cells were fabricated on Pilkington TEC 7 glass coated with a sputter deposited HRT layer of ZnO:Al or SnO 2 . In some cases O 2 was added to the Ar sputter gas to increase the resistivity of the HRT buffer layers. Film properties were optimized for HRT performance by adjustments in the substrate deposition temperature, sputter gas pressure, and RF power. Best results have been obtained with reactively sputtered ZnO:Al with 2 % O 2 in Ar.