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

Abstract

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 (τ_r)/fall time (τ_f) 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.