Alleviating trade-off between responsivity and response speed of Ga2O3 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 Ga2O3 a promising candidate in the application of solar-blind photodetectors. However, Ga2O3 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 Ga2O3 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 × 107, a high R of 236.10 A W–1, a high rejection ratio (R254nm/R365nm) of 1.98 × 105, and a fast decay speed of 50 ms. Such excellent comprehensive performance ranks it into the top level among similar Ga2O3 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 Ga2O3 solar-blind photodetectors. (Figure presented.).