Synthesis of multiphase MoS2 heterostructures using temperature-controlled plasma-sulfurization for photodetector applications.

Two-dimensional (2D) materials exhibit outstanding performance in photodetectors because of their excellent optical and electronic properties. Specifically, 2D-MoS2, a transition metal dichalcogenide, is a prominent candidate for flexible and portable photodetectors based on its inherent phase-dependent tunable optical band gap properties. This research focused on creating high-performance photodetectors by carefully arranging out-of-plane 2D heterostructures. The process involved stacking different phases of MoS2 (1T and 2H) using controlled temperature during plasma-enhanced chemical vapor deposition. Among the various phase combinations, the best photocurrent response was obtained for the 1T/2H-MoS2 heterostructure, which exhibited an approximately two-fold higher photocurrent than the 2H/1T-MoS2 heterostructure and 2H/2H-MoS2 monostructure. The 1T/2H-MoS2 heterostructure exhibited a higher photoresponse than the monostructured MoS2 of the same thickness (1T/1T- and 2H/2H-MoS2, respectively). The effect of the stacking sequences of different phases was examined, and their photoperformances were investigated. This study demonstrates that phase engineering in 2D-MoS2 van der Waals heterostructures has significant potential for developing high-performance photodetectors.

Low-Temperature and Large-Scale Production of a Transition Metal Sulfide Vertical Heterostructure and Its Application for Photodetectors.

The conventional synthesis of two-dimensional (2D) transition metal dichalcogenide (TMDC) heterostructures is low yielding and lack the heterojunction interface quality. The chemical vapor deposition (CVD) techniques have achieved high-quality heterostructure interfaces but require a high synthesis temperature (>600 °C) and have a low yield of heterostructures. Therefore, the large scale and high interface quality of TMDC heterojunctions using low-temperature synthesis methods are in demand. Here, high-quality, wafer-scale MoS2 and WS2 heterostructures with 2D interfaces were prepared by a one-step sulfurization of the molybdenum (Mo) and tungsten (W) precursors via plasma-enhanced CVD at a relatively low temperature (150 °C). The 4 inch wafer-scale synthesis of the MoS2-WS2 heterostructures was validated using various spectroscopic and microscopic techniques. Further, the photocurrent generation and photoswitching phenomenon of the so-obtained MoS2-WS2 heterostructures were studied. The photodevice prepared by the MoS2-WS2 heterostructures at 150 °C showed a photoresponsivity of 83.75 mA/W. The excellent photoresponse and faster photoswitching highlight the advantage of MoS2-WS2 heterostructures toward advanced photodetectors.