Deep-ultraviolet SnO₂ nanowire phototransistors with an ultrahigh responsivity

The effect of interfacial charges between a semiconductor and a dielectric is absolutely crucial for high-performance phototransistors. In this paper, we report a novel deep-ultraviolet photodetector based on one-dimensional SnO₂ nanowires (NWs) phototransistors with an ion-gel as the surrounding gate dielectric. The density of trapped carriers induced by light irradiation could be significantly amplified via the use of high-efficiency surrounding electrolyte coupling, thus, enhancing the photogating effect. The as-fabricated devices demonstrated an outstanding responsivity of 2 × 10⁷ A/W under weak light illumination of 18.2 μW/cm². Based on our systematic investigation of the threshold voltage shift and photodetection performance, we present a theoretical explanation for the high-performance SnO₂ NWs phototransistors with the assistance of energy band analysis. The specific configuration and high-efficiency gating of the ion-gel electrolyte were particularly interesting from a photodetection point of view, providing new insights into the design and optimization of deep ultraviolet photodetection.