Few-Layer MoS$_2$/a-Si:H Heterojunction pin-Photodiodes for extended Infrared Detection

TL;DR

This paper presents a novel heterojunction photodiode combining few-layer MoS$_2$ with amorphous silicon, achieving enhanced infrared sensitivity, stability, and spectral tunability for scalable IR sensor arrays.

Contribution

It introduces a new heterojunction photodiode structure with MoS$_2$ and a-Si:H, demonstrating improved IR detection and spectral switching capabilities.

Findings

Infrared sensitivity increased by up to 50 mAW$^{-1}$

Photodetectivity of 2 x 10$^{10}$ Jones achieved

Stable operation over more than six months

Abstract

Few-layer molybdenum disulfide (FL-MoS$_2$) films have been integrated into amorphous silicon (a-Si:H) pin photodetectors. To achieve this, vertical a-Si:H photodiodes were grown by plasma-enhanced chemical vapor deposition (PE-CVD) on top of large-scale synthesized and transferred homogeneous FL-MoS$_2$. This novel detector array exhibits long-term stability (more than six month) and outperforms conventional silicon-based pin photodetectors in the infrared range (IR, $\lambda$ = 2120 nm) in terms of sensitivities by up to 50 mAW$^{-1}$. Photodetectivities of up to 2 x 10$^{10}$ Jones and external quantum efficiencies of 3 % are achieved. The detectors further feature the additional functionality of bias-dependent responsivity switching between the different spectral ranges. The realization of such scalable detector arrays is an essential step towards pixelated and wavelength-selective sensors operating in the IR spectral range.