Cd doping at the CuInSe2/CdS heterojunction

The chemical composition of the CuInSe2/CdS heterojunction interface is investigated by angle resolved x-ray photoelectron spectroscopy, Auger electron spectroscopy, and secondary ion mass spectroscopy in combination with selective etching of CdS. We demonstrate that similar to0.8 monolayer of Cd is incorporated into the first 1-3 atomic layers,of the CuInSe2. This is accompanied by significant Cu depletion with respect to In in the same region. The results suggest that Cd-Cu defects heavily dope CuInSe2 surface n type and cause the observed large band bending on the CuInSe2 side of the heterojunction. (C) 2003 American Institute of Physics.