Investigation of Recombination Processes in CIGS Based Solar Cells with Submicrometer Absorber Layers

Current versus voltage and temperature (IVT) characterizations have been performed on CIGS (Cu(In,Ga)Se2 solar cells previously submitted to a chemical etching of their absorber layer. This study aims to investigate the changes in recombination paths, if any, when the absorber layer thickness is reduced. Diode parameters saturation current, ideality factor, series and parallel resistances were extracted from the IVT curves through a method based on the one-diode model. No clear evolution with thickness of the parameters was found among the etched samples. Temperature-dependent ideality factor and very high values of the saturation current activation energy were deduced from the data, denoting a tunneling-enhanced interface recombination process. A different behavior was however detected between the non etched control sample and the others that could be due to a modification of the surface of the CIGS layer during the very early stages of the etch.