• CVD oxygen flow tunes oxygen vacancy in Ga 2 O 3 microwires. • Optimal O-vacancies boost photocurrent and responsivity. • Surface oxygen adsorption speeds up charge separation and response. • Single microwire device achieves high detectivity for solar-blind UV. Highly crystalline Ga 2 O 3 microwires were synthesized on sapphire substrates via a one-step chemical vapor deposition process. The concentration of oxygen vacancies was effectively controlled by adjusting the gas flow rate during growth. Single microwire-based solar-blind photodetectors were fabricated, and their photoelectronic properties were evaluated under different oxygen flow conditions. The device grown under an O 2 flow rate of 2 sccm exhibited exceptional performance. Under a 20 V bias and 255 nm illumination, it achieved a responsivity of 1.17 A/W, with a solar-blind-to-UV rejection ratio of 49.7 and a solar-blind-to-visible rejection ratio of 1.61 × 10 3 . The corresponding external quantum efficiency and specific detectivity were 572 % and 4.6 × 10 12 Jones, respectively. This enhanced performance is attributed to an optimal concentration of oxygen vacancies, which act as donor states to enhance photocurrent, while the high surface area of the microwire promotes an oxygen adsorption–desorption mechanism that improves response speed. This work demonstrates that precise control of oxygen vacancies during growth is a promising strategy for producing high-performance solar-blind photodetectors.
Han et al. (Fri,) studied this question.