Ultrafast and Polarization-Sensitive\nReS₂/ReSe₂ Heterostructure Photodetectors with\nAmbipolar Photoresponse

Abstract

Recently, two-dimensional (2D) van der Waals (vdWs) heterostructures\nprovided excellent and fascinating platforms for advanced engineering\nin high-performance optoelectronic devices. Herein, novel ReS₂/ReSe₂ heterojunction phototransistors are constructed\nand explored systematically that display high responsivity, wavelength-dependent\nambipolar photoresponse (negative and positive), ultrafast and polarization-sensitive\ndetection capability. This photodetector exhibits a positive photoresponse\nfrom UV to visible spectrum (760 nm) with high photoresponsivities\nabout 126.56 and 16.24 A/W under 350 and 638 nm light illumination,\nrespectively, with a negative photoresponse over 760 nm, which is\nmainly ascribed to the ambipolar photoresponse modulated by gate voltage.\nIn addition, profound linear polarization sensitivity is demonstrated\nwith a dichroic ratio of about ∼1.2 at 638 nm and up to ∼2.0\nat 980 nm, primarily owing to the wavelength-dependent absorption\nanisotropy and the stagger alignment of the crystal. Beyond static\nphotodetection, the dynamic photoresponse of this vdWs device presents\nan ultrafast and repeatable photoswitching performance with a cutoff\nfrequency (<i>f</i>_3dB) exceeding 100 kHz. Overall,\nthis study reveals the great potential of 2D ReX₂-based\nvdWs heterostructures for high-performance, ultrafast, and polarization-sensitive\nbroadband photodetectors.