Fast Yet Quantum-Efficient Few-Layer Vertical MoS2 Photodetectors

TL;DR

This paper presents vertical few-layer MoS2 photodetectors that are both fast and quantum-efficient, leveraging a vertical design to enhance light absorption and carrier collection, suitable for high-performance nanoelectronics.

Contribution

The work introduces a vertical MoS2 photodetector architecture that achieves high efficiency and speed, with reduced carrier collection time, outperforming previous in-plane and vertical designs.

Findings

Photoresponse up to 0.11 A/W

External quantum efficiency up to 30%

Response time of 60 ns and cutoff frequency of 5.5 MHz

Abstract

Semiconducting 2D materials, such as molybdenum disulfide (MoS2) and other members of the transition metal dichalcogenide family, have emerged as promising materials for applications in high performance nanoelectronics that exhibit excellent electrical and optical properties. Highly efficient photocurrent (PC) generation is reported in vertical few layer MoS2 devices contacted with semitransparent metallic electrodes. The light absorption of the device can be improved by fabricating vertical photodevices using few layer flakes, achieving a photoresponse of up to 0.11 A/W and an external quantum efficiency (EQE) of up to 30%. Because of the vertical design, the distance between electrodes can be kept in the range of a few nanometers, thus substantially reducing the collection time of photogenerated carriers and increasing the efficiency of the devices. The wavelength dependent PC, photoresponsivity, and EQE are measured over a photon energy range from 1.24 to 2.58 eV. Compared to previous in plane and vertical devices, these vertical few layer MoS2 photodevices exhibit very short response time, 60 ns, and a cutoff frequency of 5.5 MHz, while maintaining high photoresponsivity.