Two-dimensional transition metal dichalcogenides (TMDs) have shown great potential for application in the next generation of electronics and optoelectronics due to their atomically thin thickness, tunable band gap, and strong light-matter interaction. However, their practical application is still limited by challenges such as the constraints of high-temperature synthesis processes, compatibility issues of p-type/n-type doping strategies, and insufficient nanoscale patterning accuracy. Plasma treatment has become a key technology to break through these bottlenecks with its unique advantages such as low-temperature operation capability, generation of highly active reactive species and precise controllability of multiple parameters. This review comprehensively reviews the latest progress in plasma engineering of TMDs (MoS₂, WS₂, WSe₂, etc.) based on a systematic “fundamental process–property modulation–device innovation” framework. The key plasma technologies are highlighted: plasma-enhanced chemical vapor deposition (PECVD) for low-temperature growth, bidirectional doping achieved through active species regulation, atomic layer precision etching, and defect engineering. The regulation mechanism of plasma on the intrinsic properties of materials is systematically analyzed, including electronic structure modification, optical property optimization (such as photoluminescence enhancement) and structural feature evolution. It then reveals how plasma technology promotes device innovation: achieving customizable structures (p-n junctions, sub-10 nanometer channels), optimizing interface properties (reducing contact resistance, integrating high-k dielectrics), and significantly improving the performance of gas sensors, photodetectors and neuromorphic computing systems. Finally, this article looks forward to future research directions, emphasizing that plasma technology is a versatile and indispensable platform for promoting TMDs towards practical applications.

Two-dimensional transition metal dichalcogenides (2D TMDs) with metal-insulator transition (MIT) have garnered significant attention for their potential in elucidating electronic state regulation mechanisms and advancing novel electronic devices, ultra-low power switches, and memory technologies. Generally, MIT behavior is often obscured by Schottky barrier (SB). Previous approaches, such as using four-probe methods or barrier-free van der Waals (vdW) semimetal electrodes, have aimed to eliminate the influence of SB on MIT. However, these methods are either complicated by intricate fabrication and testing processes or limited by the availability of suitable semimetal electrodes. Here, we demonstrated a bias voltage (V_ds)-switchable MIT in pure vdW TMDs field-effect transistors (FETs) for the first time, driven by V_ds-tunable effective SB and charge injection mechanisms. We identified a conversion voltage (V_conversion), which can be reduced by eliminating extra tunneling barriers introduced by vdW gaps before the inherent SB. This work offers comprehensive perspective on how tunneling barriers influence MIT and introduces a straightforward approach to fabricating MIT-based electronic devices.

Atomically thin two-dimensional (2D) materials are promising candidates to develop flash memories with premium performances as compared to conventional bulk materials, because of their ultra-thin thickness and highly tunable electrical properties. So far, most of the reported 2D material based flash memories work in the uni-polar mode, which usually further integrate additional local gate to achieve bi-polar function. However, such approach is volatile, meaning that the gate bias has to be applied persistently to maintain the polarity change and thus increases the power consumption. Here, we report a bi-polar memory based on MoTe₂/h-BN/graphene semi-floating gate (SFG) heterostructure, which has non-volatile and dynamically tunable polarity. The SFG configuration has the channel layer of MoTe₂ and dielectric layer of h-BN half-stacked on the floating gate layer of graphene. The off-graphene half of the MoTe₂ channel can be tuned between n-type and p-type by simultaneously applying ultraviolet (UV) illumination and electrical field through the back gate, which maintains this polarity after the removal of both stimuli. As a result, the SFG memory can work in the non-volatile bi-polar mode, with a on/off ratio of ~ 100 and switching speed of 1 ms. On the other hand, the on-graphene half of the MoTe₂ channel remains n-type under UV illumination and electrical bias, so that the MoTe₂ full floating gate memory maintains n-type, which implements the integration of both n- and p-type memories in a single 2D heterostructure. This capability provides great flexibility for memory devices adapting in various emerging applications.

Flash memories and semiconductor p-n junctions are two elementary but incompatible building blocks of most electronic and optoelectronic devices. The pressing demand to efficiently transfer massive data between memories and logic circuits, as well as for high data storage capability and device integration density, has fueled the rapid growth of technique and material innovations. Two-dimensional (2D) materials are considered as one of the most promising candidates to solve this challenge. However, a key aspect for 2D materials to build functional devices requires effective and accurate control of the carrier polarity, concentration and spatial distribution in the atomically thin structures. Here, a non-volatile opto-electrical doping approach is demonstrated, which enables reversibly writing spatially resolved doping patterns in the MoTe₂ conductance channel through a MoTe₂/hexagonal boron nitride (h-BN) heterostructure. Based on the doping effect induced by the combination of electrostatic modulation and ultraviolet light illumination, a 3-bit flash memory and various homojunctions on the same MoTe₂/BN heterostructure are successfully developed. The flash memory achieved 8 well distinguished memory states with a maximum on/off ratio over 10⁴. Each state showed negligible decay during the retention time of 2,400 s. The heterostructure also allowed the formation of p-p, n-n, p-n, and n-p homojunctions and the free transition among these states. The MoTe₂ p-n homojunction with a rectification ratio of 10³ exhibited excellent photodetection and photovoltaic performance. Having the memory device and p-n junction built on the same structure makes it possible to bring memory and computational circuit on the same chip, one step further to realize near-memory computing.