High Performance MoS2 Phototransistors Photogated by PN Junction

TL;DR

This paper presents a high-performance MoS2 phototransistor that uses a silicon PN junction to enhance photoresponse, offering a new design approach for efficient, low-power photodetectors with potential for further improvements.

Contribution

The work introduces a novel MoS2 phototransistor architecture integrating a silicon PN junction, separating light absorption from electrical response for improved performance.

Findings

High photoresponse achieved in MoS2 phototransistor

Analytical model matches experimental data

Design enables low-power, high-sensitivity photodetectors

Abstract

Photodetectors based on two-dimensional (2D) atomically thin semiconductors suffer from low light absorption, limiting their potential for practical applications. In this work, we demonstrate a high-performance MoS2 phototransistors by integrating few-layer MoS2 on a PN junction formed in a silicon (Si) substrate. The photovoltage created in the PN junction under light illumination electrically gates the MoS2 channel, creating a strong photoresponse in MoS2. We present an analytical model for the photoresponse of our device and show that it is in good agreement with measured experimental photocurrent in MoS2 and photovoltage in the Si PN junction. This device structure separates light absorption and electrical response functions, which provides us an opportunity to design new types of photodetectors. For example, incorporating ferroelectric materials into the gate structure can produce a negative capacitance that boosts gate voltage, enabling low power, high sensitivity phototransistor; this, combined with separating light absorption and electrical functions, enables advanced high-performance photodetectors.