Structural, optical property and solar-blind photoelectric detection performance of high-quality Mg-doped β-Ga2O3 thin films prepared using RF magnetron sputtering

Abstract

β-Ga₂O₃ thin films with different Mg doping concentrations were fabricated on c-plane sapphire and (100) silicon substrates by magnetron sputtering, followed by an 800 °C annealing in Ar for 1 h. Microstructure, surface morphology, film composition, optical property, and the optoelectronic detection performance of the obtained films were systematically investigated. The results show that with the increasing of Mg doping concentration, the surface roughness and average crystallite size of the films first decrease and then increase; the crystallization quality first improves, reaches the best at a doping concentration of 1.01 at%, and then deteriorates; while the band gap gradually increases. The photoluminescent peak intensity first decreases and then increases with the increase of Mg doping concentration, indicating that oxygen-related defects in the β-Ga₂O₃ films decrease and then increase. The increase in the doping concentration can improve the photoelectric performance, and the device performance is optimal at 1.01 at%, with a high Photo-to-Dark Current Ratio of up to 1.25 × 10⁴, short response and fall times, and exhibits a relatively high responsivity, detectivity, and external quantum efficiency of 2.46 A/W, 1.76 × 10¹² Jones, and 1200 %, respectively. In addition, a simple UV optical power density meter was successfully constructed, demonstrating the accurate detection ability of the optical power density. This study provides an important basis for the application of Mg-doped β-Ga₂O₃ films in the field of ultraviolet detection.