Self-powered and temperature-tunable infrared-visible photodetector based on a VO2/Si heterojunction

Abstract

In this work type-III heterojunction based on a pulsed laser (PLD) deposited vanadium dioxide (VO2) and p-type silicon (p-Si) substrate was realized. The device showed large self-powered and room temperature photo-response to IR (950 nm), green (515 nm), and blue (456 nm) LEDs. A short circuit current (Isc) of ~3 µA and an open-circuit voltage (Voc) of ~-120 mV is observed under IR LED illumination. The work function data in literature along with the sign of Voc measurement was used to sketch the energy band diagram of the heterojunction. The temperature-dependent Isc properties of the junction, contrary to conventional photodetectors, showed an initial rise and then sharp transition from maximum (3.5 μA) to almost zero near 337 K, corresponding to a metal-insulator phase transition, paving the way for photodetectors with temperature tunable photo-response.