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

Abstract
The contact formation of thin-filmepitaxial CuInSe 2 (001) with a physical-vapor-deposited CdS layer is presented in this work. Synchrotron-excited photoelectron spectroscopy was used for this investigation. The epitaxial CuInSe 2 films contain a surface layer of reduced Cu stoichiometry similar to the ordered defect compound CuIn 3 Se 5 . 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 surfacecopper content have a major impact on the valence band offset of CuIn 3 Se 5 , respectively, CuInSe 2 with CdS.