# A Broad-Band Self-Powered Photodetector Based on a MoTe2/Bi2Te3 Heterojunction for Optical Imaging and Bias-Controlled Signal Modulation

## TL;DR

A new self-powered photodetector using a MoTe2/Bi2Te3 heterojunction shows broad light detection and fast response, suitable for optical imaging and signal modulation.

## Contribution

A MoTe2/Bi2Te3 heterojunction is demonstrated with broad spectral response and bias-controlled signal modulation for self-powered photodetection.

## Key findings

- The device shows a photovoltaic response from 405 to 1550 nm with a responsivity of 1.38 A/W at 532 nm.
- Under reverse bias, responsivity increases to 36.22 A/W with fast rise and decay times of 32 ms and 33 ms.
- The device enables optical imaging and bias-controlled signal modulation due to its optical switching ratios.

## Abstract

Self-powered photodetectors are highly demanded in applications but often suffer from limited spectral absorption, slow response speed, and high dark currents. Two-dimensional van der Waals heterostructures have emerged as promising candidates owing to their designable structures and excellent performance. Herein, we construct a MoTe2/Bi2Te3 heterostructure and investigate its photoelectric properties. At zero bias, it exhibits a broad photovoltaic response ranging from 405 to 1550 nm. Benefiting from the interfacial built-in electric field, it achieves a responsivity of 1.38 A/W and a detectivity of 1.90 × 1012 Jones at 532 nm and retains 174.56 mA/W and 2.4 × 1011 Jones at 1060 nm, together with a low dark current of 1.6 × 10−12 A. Upon a reverse bias of −1 V and 532 nm laser illumination at an intensity of 19.0 W/m2, the responsivity is further boosted to 36.22 A/W, accompanied by rise and decay times of 32 ms and 33 ms, respectively. Taking advantage of the distinct optical switching ratios at zero/non-zero biases, application in optical imaging and bias-controlled signal modulation is realized, highlighting the heterojunction’s potential as a broadband self-powered photodetector.