ReS₂/WSe₂ Type II Heterojunction Phototransitors with Integrated van der Waals Electrodes to Achieve Ultralow Dark Current and Fast Response Time

Abstract

Recently, two-dimensional transition-metal dichalcogenides have become the focus of extensive research activities due to their remarkable physical properties such as high carrier mobility, tunable band gap, high optical response, and facile fabrication of heterostructures. In this study, we report on a type II van der Waals (vdW) heterojunction made of tungsten diselenide (WSe2) and rhenium disulfide (ReS2) with integrated vdW electrodes by using an all-dry transfer technique. The electrical rectified characteristics and photoelectrical response are analyzed in detail. Under 532 nm laser illumination, the ReS2/WSe2 phototransistor exhibits a photovoltaic effect, showing a specific detectivity of 5.4 × 1010 Jones and a fast impulse response time of 23.5/9 ms comparable to those of other devices with the similar structures. The junction is electrically tunable, and an atomically thin diode is realized under the appropriate gate bias. The atomically uniform and thin film without doping as well as integrated vdW electrodes not only simplifies the fabrication process but also enables the phototransistor to achieve ultralow dark current. The ReS2/WSe2 heterojunction exhibits an ultralow off-state current of 32.5 pA and an excellent rectification ratio of 3.83 × 104 under modulation of the back-gate voltage. This study provides new guidelines for the design and preparation of high-performance ReS2/WSe2 heterojunction optoelectronic devices.

Optimizing Thin Films and Device Structures for the Design of PbS Colloidal Quantum Dots Near-Infrared Photodetectors

“…One of the most practical strategies for addressing issues related to charge carrier trapping and photocarrier recombination is the construction of bilayer photosensitive films with II-type heterostructures based on energy band engineering. Introducing II-type heterointerfaces in photodetectors optimizes various parameters, including photocurrent gain, current noise, and photodetecting speed. , The presence of II-type heterojunctions allows for spatial separation of photoexcited electrons and holes, effectively inhibiting photocarrier recombination and resulting in higher photocurrent gain and responsivity. − Simultaneously, the heterointerfaces attenuate defect-assisted carrier trapping and recombination processes by promoting spatial carrier separation and forming a depletion region . This is beneficial for improving the photodetecting speed of photodetectors.…”