Amorphous Gallium Oxide‐Based Gate‐Tunable High‐Performance Thin Film Phototransistor for Solar‐Blind Imaging

Abstract Ga 2 O 3 ‐based solar‐blind photodetectors (PDs) are now attracting more and more attention for their potential application in optical imaging, spatial communication, etc. However, the performance of ever‐reported Ga 2 O 3 ‐based PDs is still not good enough, strongly affected by either the Ga 2 O 3 crystalline quality or the device structure, which severely limits their capability to detect extremely weak signals and achieve future applications. In this work, solar‐blind field‐effect phototransistor based on radio‐frequency‐magnetron sputtered amorphous gallium oxide thin film with ultrahigh photodetection performance are demonstrated. The key feature of the device is gate‐tunable photodetection enabling ultrahigh responsivity of 4.1 × 10 3 A W −1 , external quantum efficiency of 2 × 10 6 %, and detectivity of 2.5 × 10 13 Jones under a 70 µW cm −2 weak signal of 254 nm light due to a high internal gain and field effect control of the phototransistor. Furthermore, high‐resolution imaging is achieved for the imaging target by integrating the as‐fabricated photodetectors into the imaging system, which is the first report on solar‐blind imaging of amorphous gallium oxide photodetectors. Such field‐effect phototransistors with ultrahigh performance and excellent imaging capability address a significant step toward the feasibility and practicability of gallium oxide photodetectors in solar‐blind imaging system.