A solution to the fabrication of amorphous Ga2O3 solar‐blind photodetectors on rigid and flexible substrates at room temperature is reported. A robust improvement in the response speed is achieved by delicately controlling the oxygen flux in the reactive radio frequency magnetron sputtering process. Temporal response measurements show that the detector on quartz has a fast decay time of 19.1 µs and a responsivity of 0.19 A W−1 as well, which are even better than those single crystal Ga2O3 counterparts prepared at high temperatures. X‐ray photoelectron spectroscopy and current–voltage tests suggest that the reduced oxygen vacancy concentration and the increased Schottky barrier height jointly contribute to the faster response speed. Amorphous Ga2O3 solar‐blind photodetector is further constructed on polyethylene naphthalate substrate. The flexible devices demonstrate similar photoresponse behavior as the rigid ones, and no significant degradation of the device performance is observed in bending states and fatigue tests. The results reveal the importance of finely tuned oxygen processing gas in promoting the device performance and the applicability of room‐temperature synthesized amorphous Ga2O3 in fabrication of flexible solar‐blind photodetectors.

ZnO is a wide‐bandgap (3.37 eV at room temperature) oxide semiconductor that is attractive for its great potential in short‐wavelength optoelectronic devices, in which high quality films and heterostructures are essential for high performance. In this study, controlled growth of ZnO‐based thin films and heterostructures by molecular beam epitaxy (MBE) is demonstrated on different substrates with emphasis on interface engineering. It is revealed that ultrathin AlN or MgO interfacial layers play a key role in establishing structural and chemical compatibility between ZnO and substrates. Furthermore, a quasi‐homo buffer is introduced prior to growth of a wurtzite MgZnO epilayer to suppress the phase segregation of rock‐salt MgO, achieving wide‐range bandgap tuning from 3.3 to 4.55 eV. Finally, a visible‐blind UV detector exploiting a double heterojunction of n‐ZnO/insulator‐MgO/p‐Si and a solar‐blind UV detector using MgZnO as an active layer are fabricated by using the growth techniques discussed here.