Performance vs. microstructure in RF sputtered CdS/CdTe solar cells

In RF sputtering the film microstructure can be affected by many factors including substrate temperature, sputter gas pressure, substrate bias, and the magnetic field of the magnetron. In this paper we examine principally the effects of pressure, substrate bias, and the magnetic field of the planar magnetron sputter source on the microstructure and relate this to the performance of CdS/CdTe solar cells in which both semiconductor layers were grown by RF sputtering. With careful choice of gas pressure and magnetic field configuration, we have demonstrated an all-RF-sputtered CdS/CdTe solar cell with AM 1.5 efficiency of 11.6% as confirmed by NREL.