Multi Fermi level pinning at metal/Cu(InGa)(SeS)2 interfaces

Metal contacts to chemically etched Cu(InGa)(SeS)2 layers have been investigated using current–voltage and capacitance–voltage techniques. Oxidising chemicals enhance the Fermi level pinning at metal/Cu(InGa)(SeS)2 interfaces. The formation of a Schottky barrier at metal/p-Cu(InGa)(SeS)2 interface is dominated by Fermi level pinning at one of the four levels, 0.77±0.02, 0.84±0.02, 0.93±0.02 and 1.03±0.02 eV above the valence band maximum. These observed levels determined from current–voltage measurements show a good agreement with some of the previously published photoluminescence, deep level transient spectroscopy and photo acoustic spectroscopy observations. The capacitance–voltage measurements showed that this material has near ideal doping concentration of 1.0×1016 cm−3 for fabricating solar cell devices.