Rapid thermal processing of ZnTe:Cu contacted CdTe solar cells

Cadmium telluride (CdTe) is a leading absorber for thin-film solar cells. However, state-of-the art open circuit voltages (V_oc) of CdTe thin film solar cells fall ~350 mV below the value expected based on the band gap of CdTe. One of the reasons is due to barriers at the back contact. In this paper, we report on the development of a the back contact process for ZnTe:Cu contacted device that employs rapid thermal processing (RTP) to precisely control the activation and distribution of Cu. It is shown that 30 s annealing steps significantly improve fill factor and V_oc without compromising the current density. Devices with >14% efficiency and >825 mV V_oc are obtained under optimal conditions.