Performance Of MoS2 Field-effect Transistors Research Articles

General Approach for Two-Dimensional Rare-Earth Oxyhalides with High Gate Dielectric Performance.

Two-dimensional (2D) rare-earth oxyhalides (REOXs) with novel properties offer fascinating opportunities for fundamental research and applications. The preparation of 2D REOX nanoflakes and heterostructures is crucial for revealing their intrinsic properties and realizing high-performance devices. However, it is still a great challenge to fabricate 2D REOX using a general approach. Herein, we design a facile strategy to prepare 2D LnOCl (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy) nanoflakes using the molten salt method assisted by the substrate. A dual-driving mechanism was proposed in which the lateral growth could be guaranteed by the quasi-layered structure of LnOCl and the interaction between the nanoflakes and the substrate. Furthermore, this strategy has also been successfully applied for block-by-block epitaxial growth of diverse lateral heterostructures and superlattice. More significantly, the high performance of MoS2 field-effect transistors with LaOCl nanoflake as the gate dielectric was demonstrated, exhibiting competitive device characteristics of high on/off ratios up to 107 and low subthreshold swings down to 77.1 mV dec-1. This work offers a deep understanding of the growth of 2D REOX and heterostructures, shedding new light on the potential applications in future electronic devices.

Evolution Application of Two-Dimensional MoS2-Based Field-Effect Transistors

High-performance and low-power field-effect transistors (FETs) are the basis of integrated circuit fields, which undoubtedly require researchers to find better film channel layer materials and improve device structure technology. MoS2 has recently shown a special two-dimensional (2D) structure and superior photoelectric performance, and it has shown new potential for next-generation electronics. However, the natural atomic layer thickness and large specific surface area of MoS2 make the contact interface and dielectric interface have a great influence on the performance of MoS2 FET. Thus, we focus on its main performance improvement strategies, including optimizing the contact behavior, regulating the conductive channel, and rationalizing the dielectric layer. On this basis, we summarize the applications of 2D MoS2 FETs in key and emerging fields, specifically involving logic, RF circuits, optoelectronic devices, biosensors, piezoelectric devices, and synaptic transistors. As a whole, we discuss the state-of-the-art, key merits, and limitations of each of these 2D MoS2-based FET systems, and prospects in the future.

High mobility field-effect transistors based on MoS2 crystals grown by the flux method

Two-dimensional (2D) molybdenum disulphide (MoS2) transition metal dichalcogenides (TMDs) have great potential for use in optical and electronic device applications; however, the performance of MoS2 is limited by its crystal quality, which serves as a measure of the defects and grain boundaries in the grown material. Therefore, the high-quality growth of MoS2 crystals continues to be a critical issue. In this context, we propose the formation of high-quality MoS2 crystals via the flux method. The resulting electrical properties demonstrate the significant impact of crystal morphology on the performance of MoS2 field-effect transistors. MoS2 made with a relatively higher concentration of sulphur (a molar ratio of 2.2) and at a cooling rate of 2.5 °C h−1 yielded good quality and optimally sized crystals. The room-temperature and low-temperature (77 K) electrical transport properties of MoS2 field-effect transistors (FETs) were studied in detail, with and without the use of a hexagonal boron nitride (h-BN) dielectric to address the mobility degradation issue due to scattering at the SiO2/2D material interface. A maximum field-effect mobility of 113 cm2 V−1 s−1 was achieved at 77 K for the MoS2/h-BN FET following high-quality crystal formation by the flux method. Our results confirm the achievement of large-scale high-quality crystal growth with reduced defect density using the flux method and are key to achieving higher mobility in MoS2 FET devices in parallel with commercially accessible MoS2 crystals.

A photolithographic method for fabricating electron devices based on MOCVD-grown MoS2

In modern electronics, two-dimensional (2D) materials which possess atomically thin layers and periodic network structures have emerged as a new paradigm of materials with a lot of potentials. To fully realize the important commercial applications that 2D materials in modern electronics, one of the key issues, such as development of adequate lithographic processing for 2D materials, must be resolved. Here, we report an unprecedented and reliable photolithographic process for large-area patterning of molybdenum disulfide (MoS2) films on both SiO2/Si and polymer substrates, as well as a lift-off of deposited metals on MoS2 films using an Irgacure 651-doped poly(methyl methacrylate) resist and a water-free developer. To verify the feasibility of our process, the fabrication and device performance of MoS2 field-effect transistors (FETs) is also presented. We expect the proposed method to provide a reliable route to device fabrication with 2D materials and to be an important step toward their commercialization.

Effect of Dielectric Interface on the Performance of MoS2 Transistors.

Because of their wide bandgap and ultrathin body properties, two-dimensional materials are currently being pursued for next-generation electronic and optoelectronic applications. Although there have been increasing numbers of studies on improving the performance of MoS2 field-effect transistors (FETs) using various methods, the dielectric interface, which plays a decisive role in determining the mobility, interface traps, and thermal transport of MoS2 FETs, has not been well explored and understood. In this article, we present a comprehensive experimental study on the effect of high-k dielectrics on the performance of few-layer MoS2 FETs from 300 to 4.3 K. Results show that Al2O3/HfO2 could boost the mobility and drain current. Meanwhile, MoS2 transistors with Al2O3/HfO2 demonstrate a 2× reduction in oxide trap density compared to that of the devices with the conventional SiO2 substrate. Also, we observe a negative differential resistance effect on the device with 1 μm-channel length when using conventional SiO2 as the gate dielectric due to self-heating, and this is effectively eliminated by using the Al2O3/HfO2 gate dielectric. This dielectric engineering provides a highly viable route to realizing high-performance transition metal dichalcogenide-based FETs.