Gate-Tunable Multi-Band van der Waals Photodetector and Polarization Sensor

TL;DR

This paper presents a van der Waals material-based photodetector with tunable spectral response and polarization sensitivity, enabling versatile optical applications at room temperature.

Contribution

It introduces a multi-functional, gate-tunable photodetector with switchable spectral and polarization responses using all van der Waals materials, overcoming traditional material engineering challenges.

Findings

Achieves broadband detection from visible to mid-wave infrared.

Demonstrates polarization sensitivity modulation between horizontal, vertical, and nonpolarizing modes.

Provides high detectivity (>10^9 cmHz^1/2W^-1) and fast response (~1 MHz).

Abstract

A single photodetector with tunable detection wavelengths and polarization sensitivity can potentially be harnessed for diverse optical applications ranging from imaging and sensing to telecommunications. Such a device will require the combination of multiple material systems with different structures, bandgaps, and photoelectrical responses, which is extremely difficult to engineer using traditional epitaxial films. Here, we develop a multi-functional and high-performance photosensor using all van der Waals materials. The device features a gate-tunable spectral response that is switchable between near-infrared/visible and short-/mid-wave infrared, as well as broadband operation, at room temperature. The linear polarization sensitivity in the telecommunications O-band can also be directly modulated between horizontal, vertical, and nonpolarizing modes. These effects originate from the balance of photocurrent generation in two of the active layers that can be manipulated by an electric field. The photodetector features high detectivity (>109 cmHz1/2W-1) together with fast operation speed (~ 1 MHz) and can be further exploited for dual visible and infrared imaging.