High-Performance Mid-IR to Deep-UV van der Waals Photodetectors Capable of Local Spectroscopy at Room Temperature

The ability to perform broadband optical spectroscopywith subdiffraction-limit resolution is highly sought-after for a widerange of critical applications. However, sophisticated near-fieldtechniques are currently required to achieve this goal. We bypassthis challenge by demonstrating an extremely broadband photo-detector based on a two-dimensional (2D) van der Waalsheterostructure that is sensitive to light across over a decade inenergy from the mid-infrared (MIR) to deep-ultraviolet (DUV) atroom temperature. The devices feature high detectivity (>109cmHz1/2W-1) together with high bandwidth (2.1 MHz). The active area can be further miniaturized to submicron dimensions, farbelow the diffraction limit for the longest detectable wavelength of 4.1 mu m, enabling such devices for facile measurements of localoptical properties on atomic-layer-thickness samples placed in close proximity. This work can lead to the development of low-costand high-throughput photosensors for hyperspectral imaging at the nanoscale.