Oxygen vacancies modulating performance for Ga2O3 solar-blind photodetectors via low-cost mist chemical vapor deposition

Abstract

The wide bandgap and excellent chemical and physical properties of gallium oxide (Ga2O3) make it an ideal and natural material for solar-blind photodetectors (SBPDs). However, the development of Ga2O3-based SBPDs in practical applications was hindered by intrinsic oxygen vacancies (VO) in Ga2O3 films, high process requirements, and expensive equipment. Here, VO concentration in the films can be regulated by the introducing of O2 in the carrier gases using the mist chemical vapor deposition (Mist-CVD), which has the benefits of low cost, vacuum-free, and easy procedure. The high-performance Ga2O3 films exhibit a single-crystal tendency and low VO concentration under the Ar (1 L/min) and O2 (0.5 L/min) flow rates at 600 °C. The photodetectors exhibit a large photo-to-dark current ratio of 3.0 × 107, a high specific detectivity of 3.06 ×1011 Jones, and a fast response speed of 0.528/0.158 s at 500 μWcm−2 light intensities at 5 V. The mechanism of VO regulation in Ga2O3 films was demonstrated by adjusting the carrier gas flow rates. We also clarified the effect of VO on the dark current and photocurrents of the devices. The low-cost and straightforward Mist-CVD can provide an effective method to grow high-quality Ga2O3 films, further facilitating their practical application.