Resistance dependence of photovoltaic effect in Au/SrTiO3:Nb(0.5 wt %) Schottky junctions

Photoresponse in the Au/SrTiO3:0.5 wt % Nb Schottky junction with an electric field–tunable resistance between ∼70 kΩ and ∼900 MΩ has been experimentally studied. The most remarkable observation is the strong dependence of the open-circuit photovoltage on junction resistance and the invariance of the short-circuit photocurrent during resistance switching. These results, combined with a theoretical calculation based on the equivalent circuit model consisting of a diode in parallel with a resistor, suggest the occurrence of filamentary conductive channels across the interface of the junction under the impact of electric pulses, whereas the remaining Schottky barrier keeps completely unchanged.