Van der Waals Epitaxial Trilayer MoS₂ Crystals for High‐Speed Electronics

Abstract

Two‐dimensional MoS2 field‐effect transistors (FETs) have great potential for next‐generation electronics due to their excellent electronic properties with an atomic thin channel. However, multiple challenges exist for the monolayer MoS2 channel, including interface scattering and ohmic contact. In this work, well‐controlled trilayer MoS2 with high mobility and large single crystals is successfully grown on soda‐lime glass substrates using chemical vapor deposition, with a lateral size of up to 148 µm, which is the largest reported size to date. A record high on/off ratio of ≈1012 and a high carrier mobility of 62 cm2 V−1 s−1 of trilayer MoS2 FETs are demonstrated, showing notable advantages compared with the monolayer counterpart. The long‐standing issue of monolayer MoS2 performance degradation from physical vapor deposited metal contact can be mitigated by the trilayer MoS2 channel, achieving the lowest contact resistance of 350 Ω µm using the common method of e‐beam evaporated Ni. Moreover, 40‐nm channel‐length trilayer MoS2 FETs using ultrathin HfLaO dielectrics exhibit a high current of 589 µA µm−1 at a supply voltage of 1 V at room temperature, which increases to 1162 µA µm−1 at 4.3 K, the highest among those using commonly evaporated metal. Record high electron saturation velocity of 4.2 × 106 cm s−1 can be achieved at room temperature.

Layer-Dependent NO2-Sensing Performance in MoS2 for Room-Temperature Monitoring

“…Using a wet transfer method, , a poly­(methyl methacrylate) (PMMA, 950, A4) layer was initially spin-coated on the MoS 2 /SiO 2 /Si substrate surface as the transfer scaffold. Subsequently, the PMMA/MoS 2 film edges were scraped by using tweezers to create a gap between the film and the SiO 2 /Si substrate.…”

“…The E 2g 1 peak of the BL MoS 2 has a distinct redshift in comparison with that of the ML one. 25,26 Additionally, the corresponding Raman peak intensity mappings of E 2g 1 and A 1g modes for ML and BL MoS 2 manifest a rather uniform color contrast, suggesting its excellent thickness uniformity (Figure S7). Besides, higher-resolution tapping-mode atomic force microscopy (AFM) images are shown in Figure S8.…”

High-Field Electron Transport and High Saturation Velocity in Multilayer Indium Selenide Transistors

“…By contrast, 2D materials can retain their intrinsic electrical properties without compromising mobility, even at the ultimate scaling limit, due to their atomically thin nature. , The high-field transport properties and current saturation behavior of van der Waals (vdW) semiconductors have been rigorously studied for application to next-generation communication systems. − Graphene shows a high υ sat of up to 6 × 10 7 cm/s at room temperature (RT) and is a promising candidate for ultrahigh radio frequency (RF) transistors, but the zero band gap nature of graphene causes high off-current, limiting its application in integrated circuit technology. , 2D transition metal dichalcogenides (TMDCs), such as molybdenum disulfide (MoS 2 ) and tungsten disulfide (WS 2 ), show relatively low υ sat values of 3–6 × 10 6 and 3.8 × 10 6 cm/s, respectively, at RT, due to the high impurity scattering rates and corresponding low mobilities (generally <100 cm 2 /(V s)). − …”

One-Step CVD Growth and Interlayer Coupling Characteristics of Twisted MoS2/MoS2/MoS2 Homotrilayers

“…However, owing to numerous possible combinations of twist angles at different layer interfaces, the research of twisted trilayers will become more complicated than that of twisted bilayer systems. As a consequence, it is necessary to synthesize multilayer structures that includes one-interlayer-twist to verify the influence of twisted multilayer systems, which exhibit perspective potential in electronics, photodetectors, quantum photonics devices, spintronics, twistronics, and valleytronics. − Transfer methods have been utilized widely in creating twisted multilayer structures, but transfer procedure is complicated, and it is inappropriate for the systematic research of twisted angle-dependent features of 2D TMDs . In this regard, how to realize the fabrication of twisted trilayer or multilayer MoS 2 in a feasible and effective approach becomes particularly significant.…”