Efficient van der Waals layered gallium telluride-based passive photodetectors for low-power-density sensing of visible light

Gallium telluride (GaTe) is a two-dimensional (2D) semiconductor that has received considerable attention due to its potential applications in solid state optics and electronics, particularly as a sensing material in field-effect transistor (FET) photodetectors. However, there are limited reports that show its capability as a passive-type photodetector. In this work, high-quality van der Waals (vdW) layered GaTe single crystals were grown and used as the sensing material for small light power density photodetection. The vdW layered GaTe-based passive photodetector was evaluated over a wide range of power densities at various wavelengths. The measured response and decay times are similar to 1.1 s and 2.6 s, which are better than those of previously reported two-terminal passive GaTe photodetectors, and the calculated responsivities are up to 15.15, 17.67, and 17.81 A W-1 under 630 nm, 530 nm, and 460 nm irradiation, respectively. The vdW layered GaTe-based photodetector was also tested at various bias voltages to determine its performance efficiency. Although operated at a small bias voltage of 0.2 V, it is nonetheless able to detect signals as low as 0.05 W m-2, demonstrating high efficiency photodetection capability. This work demonstrates the capability of a van der Waals layered GaTe single crystal to detect a wide range of wavelengths at small power density (0.05 W m-2) while being operated at a low bias voltage of 0.2 V.