Asymmetrically Contacted Tellurium Short-Wave Infrared Photodetector with Low Dark Current and High Sensitivity at Room Temperature

Large dark current at room temperature has long been the major bottleneck that impedes the development of high-performance infrared photodetectors toward miniaturization and integration. Although infrared photodetectors based on layered 2D narrow bandgap semiconductors have shown admirable advantages compared with those based on conventional compounds, which typically suffer from the expensive cryogenic operation, it is still urgent to develop a simple but effective strategy to further reduce the dark current. Herein, a tellurium (Te)-based infrared photodetector is reported with specifically designed asymmetric electrical contact area. The deliberately introduced asymmetric electrical contact raises the electric field intensity difference in the Te channel near the drain and the source electrodes, resulting in the spontaneous asymmetric carrier diffusion under global infrared light illumination under zero bias. Specifically, the Te-based photodetector presents promising detector performance at room temperature including a low dark current of ≈1 nA, an ultrahigh photocurrent/dark current ratio of 1.57 × 10⁴, a high specific detectivity (D*) of 3.24 × 10⁹ Jones, and a relatively fast response speed of ≈720 µs at zero bias. The results prove that the simple design of asymmetric electrical contact areas can provide a promising solution to high-performance 2D semiconductor-based infrared photodetectors working at room temperature. © 2023 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH.