Studies of sputtered ZnTe films as interlayer for the CdTe thin film solar cell

The electronic interface properties of magnetron-sputtered ZnTe with CdTe and ZnO:Al have been characterized using X-ray photoelectron spectroscopy (XPS). For the CdTe/ZnTe interface, a valence band offset of 0.1±0.05 eV has been found, which is in agreement to previous investigations of ZnTe films deposited by physical vapour deposition onto CdTe substrates. The ZnO:Al/ZnTe interface is of interest as tunnelling barrier in tandem solar cells. We have found a type II band alignment with a valence band offset of 2.37±0.1 eV corresponding to a conduction band offset of 1.34±0.1 eV, which should be almost ideal for tunnelling contacts.