High-performance, reliable and self-powered solar-blind photodetectors based on GQDs/α-Ga2O3 heterojunctions

Abstract

<p>Recently, Ga2O3-based devices with a wide bandgap have gained great attention in power semiconductor devices. However, Ga2O3-based devices with the substable crystalline phase and high performances need be further developed and discussed. In this work, the α-Ga2O3 thin films and GQDs/α-Ga2O3 heterojunctions were prepared by magnetron sputtering on the transparent FTO substrates with a buffer TiO2 layer. And, the good self-powered deep-ultraviolet photodetection performance and mechanisms were discussed in the GQDs/α-Ga2O3/α-TiO2/FTO devices: its responsivity to 254 nm UV light can reach 1.72 mA/W at a bias voltage of 0 V, a normalized detection rate of 1.7 × 1010 Jones and the light-to-dark current ratio (PDCR) of ~1 were achieved due to the change of heterojunction energy band type from II to I. Moreover, the good self-powered deep UV photodetection for GQDs/α-Ga2O3/α-TiO2/FTO devices were demonstrated: a PDCR of 1.1 × 103, a self-powered responsivity (R) improved by a factor of 5 to 8.7 mA/W, the rise time (τr)/fall time (τf) of 86/39 ms, and a normalized detectivity (D*) with an improved magnitude of 1.3 to 2.3 × 1011 Jones were achieved by constructing GQDs/α-Ga2O3 heterojunctions on the outer surface of α-Ga2O3 thin film. These results can provide a reference for the future development of Ga2O3 thin film devices.<br></p>