Observation of intermixing at the buried CdS/Cu(In,Ga)Se-2 thin film solarcell heterojunction

A combination of x-ray emission spectroscopy and x-ray photoelectron spectr oscopy using high brightness synchrotron radiation has been employed to inv estigate the electronic and chemical structure of the buried CdS/Cu(In, Ga) Se-2 interface, which is the active interface in highly efficient thin film solar cells. In contrast to the conventional model of an abrupt interface, intermixing processes involving the elements S, Se, and In have been ident ified. The results shed light on the electronic structure and interface for mation processes of semiconductor heterojunctions and demonstrate a powerfu l tool for investigating buried interfaces in general. (C) 1999 American In stitute of Physics. [S0003-6951(99)03910-8].