Highly preferred orientation of Ga ₂ O ₃ films sputtered on SiC substrates for deep UV photodetector application

As a wide-bandgap semiconductor oxide material, Ga ₂ O ₃ has great application prospects in various optoelectronic fields. At present, much attention has been paid to Ga ₂ O ₃ deep ultraviolet (DUV) detectors, in which Ga ₂ O ₃ films are often poor-quality poly-crystalline or expensive mono-crystalline. In this paper, Ga ₂ O ₃ films with highly preferred orientation were deposited on hexagonal SiC (6H-SiC) substrate by magnetron sputtering, and the as-prepared Ga ₂ O ₃ films were then annealed. The influences of sputtering and annealing parameters on Ga ₂ O ₃ films were analyzed. Finally, DUV photo-detectors based on the as-obtained Ga ₂ O ₃ films were fabricated. The experimental results show, when choosing optimal sputtering parameters (RF power: 120 W, gas pressure: 1.5 Pa, film thickness: 400 nm), the sputtered Ga ₂ O ₃ films with (2¯01) highly preferred orientation after annealing at 800 °C, have good crystalline quality (FWHM = 0.108°) between single-crystal and polycrystal, showing good compromise between optoelectronic characteristics and preparation cost. The fabricated metal-semiconductor-metal (MSM) DUV photodetector operated at a bias voltage of 10 V can achieve excellent comprehensive photo-detection properties for 254 nm ultraviolet light: the responsivity, detectivity and quantum efficiency are high as 2.6 A/W, 1.6 × 10 ¹² Jones and 1265%, respectively, along with short response time of 0.26 s.