Two-dimensional HfS2-ZrS2 lateral heterojunction FETs with high rectification and photocurrent.

Multifunctional devices are an indispensable choice to fulfil the increasing demand for miniaturized and integrated circuit systems. However, bulk material-based devices encounter the challenge of miniaturized all-in-one systems with multiple functions. In this study, we designed a field effect transistor (FET) based on a monolayer HfS2-ZrS2 lateral heterojunction. It possesses simultaneous and obvious rectifying behavior and photodetection characteristics in the visible light region, such as the rectification ratio of ∼1012, photocurrent density of 13.3 nA m-1, responsivity of 57 mA W-1, and extinction ratio of 108. Notably, the rectification ratio of the single-gate FET is larger than that of the dual-gate FET under the negative gate voltage. These results indicate that monolayer lateral heterojunction-based FETs can provide an effective route to integrate rectifying and photodetection functions in single optoelectronic nanodevices.

Promising ultra-short channel transistors based on OM2S (M = Ga, In) monolayers for high performance and low power consumption.

It is hoped that two-dimensional (2D) semiconductors overcome the short channel effect and continue Moore's law. However, 2D material-based ultra-short channel devices still face the challenge of simultaneously achieving high-performance (HP) and low-power (LP) consumption. Here, we theoretically designed monolayer OM2S (M = Ga, In)-based metal-oxide-semiconductor field-effect transistors (MOSFETs), considering the gate length from 1 to 5 nm, doping concentration and underlap structure. We found that in HP (LP) applications, the on-state current exceeds 1000 (500) µA µm-1 under a 1 nm (2 nm) gate length, surpassing the needs of the International Technology Roadmap for Semiconductors (ITRS) in 2028. The subthreshold swing is close to the Boltzmann tyranny (60 mV dec-1) even as the gate length shrinks to 2 nm. The energy-delay product is two orders lower than 1.02 × 10-28 J s µm-1, indicating extraordinary high-speed manipulation and low-energy expending. Therefore, monolayer OM2S has great application in ultra-short scale devices with HP and LP consumption, and can be taken as a candidate to extend Moore's Law.

Optoelectronic properties and applications of two-dimensional layered semiconductor van der Waals heterostructures: perspective from theory.

Van der Waals heterostructures (vdWHs) which combine two different materials together have attracted extensive research attentions due to the promising applications in optoelectronic and electronic devices, the investigations from theoretical simulations can not only predict the novel properties and the interfacial coupling, but also provide essential guidance for experimental verification and fabrications. This review summarizes the recent theoretical studies on electronic and optical properties of two-dimensional semiconducting vdWHs. The characteristics of different band alignments are discussed, together with the optoelectronic modulations from external fields and the promising applications in solar cells, tunneling field-effect transistors and photodetectors. At the end of the review, the further perspective and possible research problems of the vdWHs are also presented.