Zn/Mg co-alloyed for higher photoelectric performance and unchanged spectral response in β-Ga2O3 solar-blind photodetector

Abstract

Alloying with the divalent elements (such as Zn and Mg) in β-Ga2O3 thin film can reduce the dark current and improve the photorespond speed for the solar-blind ultraviolet (UV) photodetector. However, alloying only with one element will change the spectral sensitivity out of solar-blind area due to an increase of band gap for the Mg alloyed and a decrease for Zn alloyed. Herein, a unchange band gap in β-Ga2O3 thin films were obtained by Zn/Mg co-alloyed through radio frequency magnetron sputtering. The photodetector based on Zn/Mg co-alloyed β-Ga2O3 thin films shows a low dark current (6.2 × 10−12 A at 1 V), a high ratio of photo-to-dark current (1.8 × 104), a high responsivity of 25.7 mA W−1 (to 254 nm), a high rejection ratio (R 254 nm/R 280 nm) of 1.2 × 103 under the bias of 10 V, and a fast photoresponse time (less than 0.5 μs for the rise time), which can be practically used to detect weak solar-blind deep UV signals.