Surface science studies of Cu containing back contacts for CdTe solar cells

The electronic interface properties of Cu2-xTe with CdTc have been investigated using in-situ photoelectron spectroscopy (XPS, UPS) in comparison to CdTe/Cu and CdTe/Te interfaces. A band bending towards the Fermi level as a result of the p-doping can be seen in the CdTc by depositing Cu2-xTe. Different Cu2-x Te films were prepared by varying the deposition parameters such as substrate temperature and deposition rate of the Cu and Te sources. For all Cu2-x Te/CdTe interfaces a valence band offset of 0.8 +/- 0.05 eV has been found. (C) 2007 Elsevier B.V. All rights reserved.