Photoemission study and band alignment of the CuInSe2(001)/CdS heterojunction

Abstract

The contact formation of thin-film epitaxial CuInSe2(001) with a physical-vapor-deposited CdS layer is presented in this work. Synchrotron-excited photoelectron spectroscopy was used for this investigation. The epitaxial CuInSe2 films contain a surface layer of reduced Cu stoichiometry similar to the ordered defect compound CuIn3Se5. A valence band offset of 0.79±0.15 eV has been determined for this heterojunction. The comparison to literature data indicates that neither surface orientation nor surface copper content have a major impact on the valence band offset of CuIn3Se5, respectively, CuInSe2 with CdS.