Photogating-controlled ZnO photodetector response for visible to near-infrared light

In recent years, as a direct wide band gap semiconductor, zinc oxide (ZnO) nanomaterial has attracted a lot of attention. However, the widely investigated ZnO materials are strongly limited in fast-response and broadband photodetectors due to their inherent weaknesses, so an effective structure or mechanism of ZnO nanostructure photodetector is greatly needed. In this work, a photogating-controlled photodetector based on a ZnO nanosheet-HfO₂-lightly doped Si architecture is demonstrated. Its performance was significantly improved by the photogating-controlled local field at the Si and HfO₂ interfaces compared to the findings in other published works on ZnO. Consequently, the photodetector not only effectively balances the responsivity (as high as 5.6 A W^-1) and response time (400 µs), but also broadens the wavelength response of the ZnO-based photodetectors from visible to near-infrared light range (~1200 nm). Additionally, the photogating-controlled ZnO photodetector enables high-resolution imaging both in the visible and near-infrared bands. Our photogating-controlled ZnO photodetectors not only exemplify the controllability of the gate electrode in high mobility materials but also provide a basis for the development of fast speed and high responsivity detection of high mobility materials.