Manipulating hot-electron based photovoltage generations at oxide interfaces*

To maximize efficiencies of photovoltaic devices and photodetectors, it is highly desirable to enable carrier excitation from low energy photons and extract excessive energy from hot carriers. At the LaAlO3/SrTiO3 interface contacted by metal electrodes, substantial photovoltages can be generated by photons with energy below the oxide bandgaps. This originates from the photoexcitation of hot carriers in metal and the subsequent charge separations through either hole filtering at the metal/oxide junction or the photothermoelectric effect produced in the interfacial two-dimensional electron gas. The two light-to-voltage conversion mechanisms can be locally selected and reconfigured by patterning of 2DEG using conductive atomic force microscope. With tunable band alignment, improved light absorption and giant Seebeck coefficient at oxide interface, the hot-electron enabled photovoltage generations make LaAlO3/SrTiO3 viable for programmable solar energy harvesting and thermoelectric device applications.