A 1T′-MoTe2/GaN van der Waals Schottky junction for self-powered UV imaging and optical communication

Abstract

Schottky-type self-powered UV photodetectors are promising for next-generation imaging systems. Nevertheless, conventional device fabrication using high-energy metal deposition brings unintentional interface defects, leading to deteriorated device performance and inhomogeneities. Emerging two-dimensional (2D) metallic materials offer an alternative pathway to overcoming such limitations because of their naturally passivated surfaces and the ease of combining with mature bulk semiconductors via van der Waals (vdW) integration. Here, we report the controllable preparation of MoTe₂ in the pure 1T′ phase and the fabrication of a high-performance 1T′-MoTe₂/GaN vdW Schottky photodiode. With the reduced interface states and suppressed dark current as low as 20 pA at zero bias, the photodiode exhibits a remarkable UV-to-visible (R₃₅₀/R₄₀₀) rejection ratio of 1.6 × 10⁴, a stable photoresponsivity of ∼50 mA W⁻¹ and a detectivity of 3.5 × 10¹² Jones under 360 nm illumination. The photocurrent ON/OFF ratio reaches ∼4.9 × 10⁶ under 10.5 mW irradiation (360 nm). In particular, the 1T′-MoTe₂/GaN Schottky diode shows excellent weak-light detection capability, which could detect a 3 nW 360 nm laser and the light emission from a lighter with a pronounced I_light/I_dark ratio of ∼2. Finally, the applications of the device in self-powered UV imaging and optical communication are demonstrated. These results reveal the great prospects of 2D/3D integration in multifunctional optoelectronics, which may inspire novel 2D-related devices and expand their applications in widespread fields.