Schottky barrier height switching in thin metal oxide films studied in diode and solar cell device configurations

We investigate changes in the properties of 8 nm thin metal oxide (Nb-doped SrTiO₃) films in response to relatively high voltage or light soaking under three Sun excitation. We measure the current-voltage behavior of metal|insulator|metal type diodes and use a device model to relate changes in device behavior to the metal oxide film properties. We find that the device's resistive switching is mainly associated with shifts (switching) of the metal oxide work function between high and low injection barrier states. The method presented here can be used for in situ monitoring of the contact work function and for quantifying the uniformity of this value across the device. We also discuss the effect of non-uniform work function on the apparent diode's ideality factor.