Chemical and electrical properties of ZnTe based solar cells

Abstract

ZnTe is a candidate low-cost II-VI absorber material of wide band gap (EG = 2.24 eV) with potential of enhanced open circuit voltage and application for tandem cells. Fundamental chemical and electronic properties related to the processing of ZnTe-based devices are demonstrated. We used x-ray diffraction, scanning electron microscopy and photoemission spectroscopy to analyze film structure, morphology, chemical composition and valence band structure of ZnTe/ZnSe films deposited sequential close space sublimation. Specifically, interfacial Se oxide was observed and caused band offsets apparent in the heterojunction band energy diagram. Processing steps to mitigate oxidation yielded the best cells.