Solar-blind /3-Ga2O3 photodetectors with high detectivity via semimetal Bi contacts

Solar-blind UV photodetectors based on Ga2O3 films possess important potential applications in ozone-hole detection, flame detection and corona detection. However, the performance (detectivity, response time, etc.) of Ga2O3-based photodetectors reported so far still lags behind the current commercial devices, due to the metalinduced gap states (MIGS) at the metal-semiconductor interface. Here, by contact engineering, we design an ohmic-contacted photodetector based on semimetal Bi electrodes and single-crystal /3-Ga2O3 films. The transmission electron microscopy (TEM) shows that the Bi electrode is a layered single-crystal grown on the singlecrystal Ga2O3 film by van der Waals epitaxy, providing a clean and dangling-bond-free interface. The BiGa2O3 photodetector exhibits a high responsivity of 720 A W-1 and an ultra-high specific detectivity of 4.35 x 1015 Jones under 254 nm ultraviolet light. More importantly, the device still shows high detectivity at a lower light intensity (6 mu W cm-2). Overall, the high-sensitive Bi/Ga2O3/Bi devices have great potential for future commercial solar-blind UV photodetectors.