Performance of A Single Phosphorus-doped β-Ga2O3 Microwire Solar-blind Ultraviolet Photodetector

Recently, ultraviolet(UV) photodetectors have aroused the widespread concern of researchers around the world for their wide applications in UV radiation detection, missile warning, flame detection, ozone monitoring, and environmental monitoring. Most of the solar-blind photodetectors have been realized based on the wide bandgap semiconductor materials, such as ZnMgO, AlGaN, diamond and β-Ga2O3. Compared with these semiconductor materials, β-Ga2O3 is an emerging wide bandgap semiconductor that has attracted a large amount of interest due to its ultra-large bandgap of 4.9 eV in the solar-blind range, a high breakdown field of 8 MV/cm, and high thermal stability and chemical stability. In addition, the study shows that the impurity doping can significantly improve the electrical properties of β-Ga2O3 materials. In this paper, large-scale centimeter-level phosphorus-doped β-Ga2O3 microwires were grown by chemical vapor deposition method without any catalyst. The high purity Ga2O3, P2O5, graphite powders and O2 were used as the source materials and reactant gas for the microwires growth. The surface morphology, crystal structure and composition of the microwires were studied. It was found that the length of the microwire about was 0.6-1 cm and the diameter was about 40 μm. In order to study the UV sensing characteristics of photodetector, we fabricated a metal-semiconductor-metal(MSM) structure solar-blind ultraviolet detector based on a single phosphorus doped β-Ga2O3 microwires. The results show that both the undoped β-Ga2O3 microwires and phosphorus doped β-Ga2O3 microwires have good responses to 254 nm UV light, and the photocurrent value of the device made of the microwire with phosphorus content of 2.3% is the highest. Further photoelectric test of the phosphorus doped device shows that when the optical power is 550 μW/cm2, the photocurrent is 3.1 μA, the dark current is 1.56 nA, the photo-to-dark current ratio is about 2×103, the rise and fall time are 47 ms and 31 ms, respectively, and the responsivity reaches 2.8 A/W. When the optical power is 100 μW/cm2, the optical responsivity and external quantum efficiency of the device are the largest, which are 6.57 A/W and 3213%, respectively. Meanwhile, the UV detection mechanism of the device was studied. © 2021, Science Press. All right reserved.