Native Oxide Growth on CdSeTe for Improved Back Surface Passivation

The use of native oxides have historically been used in numerous PV technologies to passivate surfaces and improve voltage and conversion efficiency. Using XPS, in this study we observe the growth of tellurium oxides on the back surface of CdSeTe films when stored in air for several weeks. We note considerable differences in the prevalence of tellurium oxides between as-deposited and chlorine-treated films. Finally, external radiative efficiency measurements show that ERE correlates strongly with increased tellurium oxide formation. This indicates that the oxide layer is passivating the back surface of CdSeTe, a crucial step towards improving the open-circuit voltage.