Enhancing the performance of β-Ga2O3 solar-blind photodetectors based on ZnGa2O4 substrate by bottom-up Zn diffusion doping

β-Ga2O3 solar-blind photodetector (SBPD) promises great potential applications in both industrial and scientific fields while it urgently needs performance optimization. Herein, the unique bottom-up Zn diffusion doping engineering was applied to fabricate an ultrahigh-performance β-Ga2O3 planar MSM SBPD. High-quality β-Ga2O3 film was grown by MOCVD heteroepitaxy technology on the cost-effective ZnGa2O4 substrate, and the high-temperature growth process successfully realized the moderate diffusion Zn doping from the substrate to the film. This low-cost one-step doping not only reduces the dark current of the device to 635 fA at 20 V, which is 103 times lower than the β-Ga2O3 film SBPD grown on a c-sapphire substrate under the same conditions, but also maintains the excellent crystal quality of the MOCVD grown film, thus brings the comprehensive performance of the device exceeding most reported β-Ga2O3 SBPDs. The device exhibits a high photo-to-dark-current ratio of 1.18 × 107, high responsivity of 72.35 A/W, considerable rejection ratio (R254 nm/R365 nm) of 107, and extremely fast decay time of 8 ms under 254 nm illumination at 20 V. This work provides novel strategies of β-Ga2O3 film optimization for the future development of high-performance photodetectors.