# Waveguide Integrated Self-Powered MoS2 Photodetectors in the Shortwave Infrared Wavelengths

## TL;DR

This paper introduces a self-powered, waveguide-integrated photodetector using MoS2 that operates efficiently in the shortwave infrared with no dark current and high responsivity.

## Contribution

The work presents a zero-bias MoS2 photodetector with record responsivity and high detectivity in the shortwave infrared using the photothermoelectric effect.

## Key findings

- The device achieves a responsivity of ∼180 V/W at 1550 nm, the highest for unbiased 2D PDs in the shortwave infrared.
- The noise equivalent power is ∼500 nW at 1 Hz and reduces to ∼0.3 nW at the Johnson limit.
- The specific detectivity (D*) reaches ∼2 × 10^10 Jones at Johnson noise-limited operation.

## Abstract

Broadband photodetectors (PDs) are essential for various
applications,
including optical communication, sensing, and imaging. Modern semiconductor
PD technologies often face challenges related to spectral coverage,
power consumption, complex manufacturing, and limited integration
with silicon electronics. As photonics technologies continue to advance
alongside growing performance demands, exploring new avenues for innovative,
cost-effective broadband PDs with reduced power consumption and manufacturing
complexity is becoming increasingly important. In this work, we present
a zero-bias, waveguide-integrated PD based on single-layer MoS2, which operates at telecom wavelengths with no dark current.
By utilizing the photothermoelectric effect combined with internal
photoemission process, our devices demonstrate a record responsivity
of ∼180 V/W at 1550 nm, the highest reported in the literature
for unbiased 2D PDs operating in the short-wave infrared. The recorded
frequency response is in the millisecond range, limited by the electrical
RC time constant. The PD noise equivalent power is ∼500 nW
at 1 Hz, dominated by 1/f noise, and is reduced to
∼0.3 nW at the Johnson limit. Consequently, the specific detectivity
(D*) is estimated to be ∼105 Jones
at the 1/f limit, reaching ∼2 × 1010 Jones at Johnson noise-limited operation. Our findings contribute
to developing high-efficiency broadband MoS2 PDs and emphasize
the potential of 2D semiconductors in advancing self-powered PDs technology.