Alleviating trade‐off between responsivity and response speed of <scp>Ga₂O₃</scp> solar‐blind photodetector via modulation of carrier redistribution and extraction accessibility

Abstract Suitable bandgap, high solar‐blind light sensitivity, and high stability against harsh environments make Ga 2 O 3 a promising candidate in the application of solar‐blind photodetectors. However, Ga 2 O 3 photodetectors, particularly those dominated by the photoconductive effect, inevitably face a trade‐off between photoresponsivity and response speed. Common methods to mitigate this trade‐off usually improve one aspect with the compromise of another. In this work, bilayer‐structure Ga 2 O 3 films are adopted for solar‐blind photodetectors to alleviate the trade‐off of photoresponsivity and response speed. The performance improvement effect of the bilayer‐structure device is credited to its favorable modulation of carrier redistribution between two layers and extraction accessibility by the electrode. Through further optimization of film crystallinity by annealing, the bilayer‐structure device acquires improved photoresponse performance, including a low dark current of 1.16 pA, a high photo to dark current ratio of 3.49 × 10 7 , a high R of 236.10 A W –1 , a high rejection ratio ( R 254nm / R 365nm ) of 1.98 × 10 5 , and a fast decay speed of 50 ms. Such excellent comprehensive performance ranks it into the top level among similar Ga 2 O 3 photodetectors dominated by the photoconductive effect. This work provides a universal and facile design to mitigate the trade‐off between photoresponsivity and response speed of Ga 2 O 3 solar‐blind photodetectors. image