Surface type conversion of CuInSe2 with H2S plasma exposure: A photoemission investigation

Abstract

Surface type conversion of CuInSe2 by H2S plasma exposure was studied by synchrotron radiation soft x-ray photoemission spectroscopy. The low power H2S plasma was generated with a commercial electron cyclotron resonance plasma source using pure H2S with the plasma exposure being performed at 400 °C. In situ photoemission measurements were acquired after each plasma exposure in order to observe changes in the valence band electronic structure as well as changes in the In 4d and Se 3d core lines. The results were correlated in order to relate changes in surface chemistry to the electronic structure. These measurements indicate that the H2S plasma exposure type converts the n-type CuInSe2 surface to a p-type surface at this elevated temperature and that the magnitude of the band bending is 0.5 eV, resulting in a homojunction interface.