Jing Zhang

In this paper, by contacting a monolayer MoSe₂ with a 2D ferromagnetic semiconductor Cr₂Ge₂Te₆, a novel spin-valley functional device that exhibits both electrical and magnetic tunability is demonstrated. This provides a new physical knob that may effectively manipulate the spin-valley polarization in the device context.

Abstract

The emergence of atomically thin valleytronic semiconductors and 2D ferromagnetic materials is opening up new technological avenues for future information storage and processing. A key fundamental challenge is to identify physical knobs that may effectively manipulate the spin-valley polarization, preferably in the device context. Here, a novel spin functional device that exhibits both electrical and magnetic tunability is fabricated, by contacting a monolayer MoSe₂ with a 2D ferromagnetic semiconductor Cr₂Ge₂Te₆. Remarkably, the valley-polarization of MoSe₂ is found to be controlled by a back-gate voltage with an appreciably enlarged valley splitting rate. At fixed gate voltages, the valley-polarization exhibits magnetic-field and temperature dependence that corroborates well with the intrinsic magnetic properties of Cr₂Ge₂Te₆, pointing to the impact of magnetic exchange interactions. Due to the interfacial arrangement, the charge-carrying trion photoemission predominates in the devices, which may be exploited to enable drift-based spin-optoelectronic devices. These results provide new insights into valley-polarization manipulation in transition metal dichalcogenides by means of ferromagnetic semiconductor proximitizing and represent an important step forward in devising field-controlled 2D magneto-optoelectronic devices.

Nature, Published online: 15 June 2022; doi:10.1038/s41586-022-04771-5

Using an interlayer bonding cleavage strategy, a two-dimensional monolayer fullerene network is prepared; its moderate bandgap makes it a potential candidate for use in two-dimensional electronic devices.

Nature, Published online: 15 June 2022; doi:10.1038/s41586-022-04715-z

High-resolution scanning tunnelling microscopy and spectroscopy are used to provide evidence for unconventional superconductivity in magic-angle twisted trilayer graphene.

A layered air-stable topological crystalline insulator (TCI) candidate, ErAsS, is designed and synthesized, which maps the atomic layers in real space to the band topology in momentum space. The distorted As atomic layer and magnetic order of ErAsS induce both the hourglass fermion surface state and the magnetic-tuned exotic phases including the possible magnetic TCI.

Abstract

Topological crystalline insulators (TCIs) with hourglass fermion surface state have attracted a lot of attention and are further enriched by crystalline symmetries and magnetic order. Here, the emergence of hourglass fermion surface state and exotic phases in the newly discovered, air-stable ErAsS single crystals are shown. In the paramagnetic phase, ErAsS is expected to be a TCI with hourglass fermion surface state protected by the nonsymmorphic symmetry. Dirac-cone-like bands and nearly linear dispersions in large energy range are experimentally observed, consistent well with theoretical calculations. Below T_N  ≈ 3.27 K, ErAsS enters a collinear antiferromagnetic state, which is a trivial insulator breaking the time-reversal symmetry. An intermediate incommensurate magnetic state appears in a narrow temperature range (3.27–3.65 K), exhibiting an abrupt change in magnetic coupling. The results reveal that ErAsS is an experimentally available TCI candidate and provide a unique platform to understand the formation of hourglass fermion surface state and explore magnetic-tuned topological phase transitions.

Negative Phototransistors

In article number 2201364, Huipeng Chen, Jishan Wu, Fangxu Yang, Wenping Hu, and co-workers report an ultrasensitive negative phototransistor based on 1D/2D molecular crystal p–n heterojunctions. This novel device exhibits a variety of intriguing properties, including superior performance parameters, accurately controllable threshold voltage, and ultrasensitive detection of weak light. The results demonstrate the fascinating promise of organic single-crystal heterostructure electronics.

Nature Photonics, Published online: 02 June 2022; doi:10.1038/s41566-022-01012-z

The strongly temperature-dependent band-edge absorption from gallium arsenide enables an optical thermometer with nanokelvin temperature resolution and microscale spatial resolution.

A review explains how resistors with memory functions are being integrated into electronics and new computer architectures.

Nature Electronics, Published online: 02 June 2022; doi:10.1038/s41928-022-00768-0

The stability of graphene-based field-effect transistors with amorphous aluminium oxide serving as the top-gate oxide can be improved by tuning the Fermilevel of the two-dimensional channel material such that it maximizes the energy distance between the charge carriers in the channel and the defect bands in the gate oxide.

Nature Electronics, Published online: 06 June 2022; doi:10.1038/s41928-022-00769-z

Transistors based on two-dimensional semiconductors suffer from electrical instabilities because charges readily get trapped in the gate oxides. As charge trapping is sensitive to the energetic alignment of the channel Fermi level to the defect bands in the oxide, the number of electrically active traps can be reduced by tuning the channel Fermi level.

In this review, the interaction principle and processing strategies of functional graphene induced by laser are summarized, especially for the regulation of optical and electrical properties. The development and challenges of laser-treated graphene in related photo- and electro-devices are also discussed, aiming to provide new valuable guidelines for rationally coordinating the structural design and functionality of graphene-based devices.

Abstract

Graphene is considered as a competitive material for the development of photo- and electrodevices because of its superior electrical and optical properties. Meanwhile, laser processing technologies with high precision, fast reaction speed, and high maneuverability are widely used for the fast and facile fabrication of functionalized graphene and relevant devices. In particular, it enables desired performance tuning, programmable structural designing, micro- or nanoscale processing, and large-scale integration for advanced graphene-based photo- and electro-related devices, which has greatly promoted the development of multiscale and multidimensional device manufacturing technology. In this review, the interaction principle and processing strategies of functional graphene prepared and treated by laser, especially for the regulation of optical and electrical properties, will be fully understood and introduced. The latest progress and reports of advanced photoelectro devices, including electric energy storage devices, generators, sensors, actuators, photodetectors, photothermal devices, and photovoltaic devices, are classified and summarized. In general, this review may provide positive and meaningful guidance for flourishing graphene-based photo- and electroindustries.

2D Crystals

Combining interface assembly of 2D organic semiconductor crystals (2DOSCs) with a poly(dimethylsiloxane)-mold-assisted selective-contact evaporation printing technique, in article number 2104166, Liqiang Li and co-workers report the fabrication of large-area, high-resolution (1271 dpi) and layer-controlled 2DOSC arrays, which would be highly meaningful for device integration.

Nature, Published online: 01 June 2022; doi:10.1038/d41586-022-01476-7

A method has been developed for fabricating thin films of the 2D insulator hexagonal boron nitride with a uniform crystal orientation. The advance makes this material a key contender for replacing silica substrates in future electronics.

Nature, Published online: 01 June 2022; doi:10.1038/s41586-022-04745-7

Using a chemical vapour deposition method, it is possible to epitaxially grow wafer-scale single-crystal trilayers of hexagonal boron nitride—an important dielectric for 2D materials—on Ni (111) foils by boron dissolution.