Large and Reconfigurable Infrared Photothermoelectric Effect at Oxide Interfaces

To maximize the photovoltaic efficiency, it is highly desirable to enable the electricity conversion from low energy photons and to extract the excessive energy from hot carriers. Here we report a large photovoltage generation at the LaAlO₃/SrTiO₃ interfaces from infrared photons with energies far below the oxide bandgaps. This effect is a result of the photoexcitation of hot carriers in metasurface electrical contacts and the subsequent thermoelectric charge separations by the interfacial two-dimensional electron gas (2DEG). Reaching a room-temperature responsivity of 4.4 V/W, such light-to-charge conversion can be spatially controlled and reconfigured through the patterning of 2DEG using conducting atomic force microscope. Compatible for broadband applications, our results demonstrate a new path toward efficient and programmable light sensing using oxide-based low-dimensional electron systems.