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 similar to 70 k Omega and similar to 900 M Omega 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. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3009285]