Intrinsic defects and metastability effects in Cu2O

Cu2O based junctions (both Schottky and ZnO/Cu2O heterojunctions) exhibit a metastable capacitance increase after illumination or reverse bias application. We show that this effect is related to the persistent photoconductivity in Cu2O substrates. To obtain a quantitative evaluation of defect properties we have measured conductivity vs T, Capacitance–Voltage, persistent photoconductivity decay and capacitance transient at different temperatures.We show that it is impossible to explain these data using an electronic mechanism only. A new model which includes the formation–dissociation of intrinsic defect complexes (VCu–VO) can give instead a better agreement with the experimental data.