A 2D Te/Mxene Schottky junction for a self-powered broadband photodetector with high polarization-sensitive imaging†

Abstract

The emerging two-dimensional (2D) material tellurium (Te) is a promising material for polarization-sensitive photodetectors (PDs) due to its narrow bandgap and inherent in-plane anisotropic crystal structure. However, the shortened photocarrier lifetime and large dark current due to the ultra-narrow bandgap and intrinsically high conductivity of Te limit the performance of photodetectors and hinder their further application in photodetection. In this paper, a Te/MXene structure was prepared by spin coating of 2D Ti₃C₂–MXene on the 2D Te nanosheets (NTs) via a hydrothermal method. The Te/MXene Schottky junction PD enables polarization-sensitive, self-powered and broadband photodetection and imaging. The device exhibits a self-powered optical response from 368 nm to 1006 nm, a maximum responsivity and a specific detectivity of 1.84 A W⁻¹ and 4.83 × 10¹² jones, respectively, a switching ratio of 2163, and a fast rise/decay time of 12.2/26.5 ms under 806 nm. The anisotropy ratio of the Te/MXene PD is increased to 4 in comparison to 1.8 of the Te PD, suggesting a notable 2222% improvement in polarization sensitivity features. Due to the in-plane low-symmetry atomic structure of the Te NTs and high absorption capacity of MXene, the fabricated high Te/MXene Schottky junction fast separates the electronic carriers to show excellent properties and polarization sensitivity. The process of creating this novel photodetector may offer a viable way to expand the use of polarization-sensitive photoelectric devices in the future.