Atomically thin 2D layered transition metal dichalcogenides (TMDs) have been extensively studied in recent years because of their appealing electrical and optical properties. Here, the fabrication of ReS2 field‐effect transistors is reported via the encapsulation of ReS2 nanosheets in a high‐κ Al2O3 dielectric environment. Low‐temperature transport measurements allow to observe a direct metal‐to‐insulator transition originating from strong electron–electron interactions. Remarkably, the photodetectors based on ReS2 exhibit gate‐tunable photoresponsivity up to 16.14 A W−1 and external quantum efficiency reaching 3168%, showing a competitive device performance to those reported in graphene, MoSe2, GaS, and GaSe‐based photodetectors. This study unambiguously distinguishes ReS2 as a new candidate for future applications in electronics and optoelectronics.

Charge-trap memory with high-κ dielectric materials is considered to be a promising candidate for next-generation memory devices. Ultrathin layered twodimensional (2D) materials like graphene and MoS2 have been receiving much attention because of their novel physical properties and potential applications in electronic devices. Here, we report on a dual-gate charge-trap memory device composed of a few-layer MoS2 channel and a three-dimensional (3D) Al2O3/HfO2/Al2O3 charge-trap gate stack. Owing to the extraordinary trapping ability of both electrons and holes in HfO2, the MoS2 memory device exhibits an unprecedented memory window exceeding 20 V. More importantly, with a back gate the window size can be effectively tuned from 15.6 to 21 V; the program/erase current ratio can reach up to 10 4 , far beyond Si-based flash memory, which allows for multi-bit information storage. Furthermore, the device shows a high mobility of 170 cm 2 V -1 s -1 , a good endurance of hundreds of cycles and a stable retention of ~28% charge loss after 10 years which is drastically lower than ever reported MoS2 flash memory. The combination of 2D materials with traditional high-κ charge-trap gate stacks opens up an exciting field of novel nonvolatile memory devices. KEYWORDS. Charge-trap memory, MoS 2 , Memory window, Dual gate, Memory characteristics 3 Atomically thin 2D materials like graphene and MoS 2 has been extensivelystudied recently because of their promising applications in optoelectronics 1, 2 , spintronics 3-7 , transparent and flexible devices [8][9][10][11][12] . Due to its remarkable properties, such as high carrier mobility and mechanical flexibility, graphene has been incorporated into nonvolatile memory structures serving as a floating gate 13,14 or a transparent channel 15 . However, owing to its zero band gap 16 , the graphene channeled memory devices typically possess a low program/erase current ratio, which significantly hinders its application in nonvolatile memory devices. Unlike graphene, MoS 2 has a transition from indirect band gap (1.2 eV) to a direct band gap (1.8 eV) in monolayer 17,18 . Its field effect transistors 19 show a high mobility of 200 cm 2 V -1 s -1 with a high on/off ratio approximately 10 8 . To potentially enhance the program/erase current ratio, attempts were made to replace graphene with MoS 2 as a channel material in a ferroelectric memory 20 or as a charge-trap layer in a graphene flash memory 21 . It was demonstrated that the monolayer MoS 2 is very sensitive to the presence of charges 14 . However, the relatively small memory window, the degraded mobility, and the insufficient trap capability in those devices require further improvement of the chargetrap stack in the MoS 2 memory device.

Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have been recently proposed as appealing candidate materials for spintronic applications owing to their distinctive atomic crystal structure and exotic physical properties arising from the large bonding anisotropy. Here we introduce the first MoS2-based spin-valves that employ monolayer MoS2 as the nonmagnetic spacer. In contrast with what is expected from the semiconducting band-structure of MoS2, the vertically sandwiched-MoS2 layers exhibit metallic behavior. This originates from their strong hybridization with the Ni and Fe atoms of the Permalloy (Py) electrode. The spin-valve effect is observed up to 240 K, with the highest magnetoresistance (MR) up to 0.73% at low temperatures. The experimental work is accompanied by the first principle electron transport calculations, which reveal an MR of ∼9% for an ideal Py/MoS2/Py junction. Our results clearly identify TMDs as a promising spacer compound in magnetic tunnel junctions and may open a new avenue for the TMDs-based spintronic applications.

MoS2 is a layered two-dimensional material with strong spin-orbit coupling and long spin lifetime, which is promising for electronic and spintronic applications. However, because of its large band gap and small electron affinity, a considerable Schottky barrier exists between MoS2 and contact metal, hindering the further study of spin transport and spin injection in MoS2. Although substantial progress has been made in improving device performance, the existence of metal-semiconductor Schottky barrier has not yet been fully understood. Here, we investigate permalloy (Py) contacts to both multilayer and monolayer MoS2. Ohmic contact is developed between multilayer MoS2 and Py electrodes with a negative Schottky barrier, which yields a high field-effect mobility exceeding 55 cm2V−1s−1 at low temperature. Further, by applying back gate voltage and inserting different thickness of Al2O3 layer between the metal and monolayer MoS2, we have achieved a good tunability of the Schottky barrier height (down to zero). These results are important in improving the performance of MoS2 transistor devices; and it may pave the way to realize spin transport and spin injection in MoS2.

Graphene/two-dimensional (2D) semiconductor heterostructures have been demonstrated to possess many advantages for electronic and optoelectronic devices. However, there are few reports about the utilization of a 2D semiconductor monolayer to tune the properties of graphene. Here, we report the fabrication and characterization of graphene p-n junctions based on graphene/MoS2 hybrid interfaces. Monolayered graphene across the monolayered MoS2 boundary is divided into n-type regions on the MoS2 and p-type regions on the SiO2 substrate. Such van der Waals heterostructure based graphene p-n junctions show good photoelectric properties. The photocurrent modulation of such devices by a single back gate is also demonstrated for the first time, which shows that the graphene on and off MoS2 regions have different responses to the gate voltage. Our results suggest that the atomic thin hybrid structure can remarkably extend the device applications.

Graphene oxide nanosheets inhibit Aβ1–42 aggregation by weakening inter-peptide interactions and reducing β-sheet contents mostly via salt bridge, hydrogen bonding and cation–π interactions with charged residues.

Recently, two-dimensional materials have been attracting increasing attention because of their novel properties and promising applications. However, the impurity doping remains a significant challenge owing to the lack of the doping strategy in the atomically thin layers. Here we report on the chromium (Cr) and manganese (Mn) doping in atomically-thin crystals grown by chemical vapor deposition. The Cr/Mn doped samples are characterized by a peak at 1.76 and 1.79 eV in photoluminescence spectra, respectively, compared with the undoped one at 1.85 eV. The field-effect transistor (FET) devices based on the Mn doping show a higher threshold voltage than that of the pure while the Cr doping exhibits the opposite behavior. Importantly, the carrier concentration in these samples displays a remarkable difference arising from the doping effect, consistent with the evolution of the FET performance. The temperature-dependent conductivity measurements further demonstrate a large variation in activation energy. The successful incorporation of the Mn and Cr impurities into the monolayer paves the way towards the high Curie temperature two-dimensional dilute magnetic semiconductors.

Alzheimer's disease (AD) is associated with the aggregation of amyloid-β (Aβ) peptides into toxic fibrillar aggregates. Finding effective inhibitors of Aβ aggregation is a crucial step for the development of drugs against AD. Recent experiments reported that dihydrochalcone (Dih), a compound extracted from the daemonorops draco tree, could effectively inhibit Aβ fibrillization and reduce Aβ cytotoxicity. However, the influence of Dih molecules on preformed Aβ fibrils and the atomic-level details of interactions between Dih and Aβ fibrils are largely unknown. In this work, we performed multiple molecular dynamics (MD) simulations for 1.2 μs in total on the Aβ17-42 protofibrils with and without Dih molecules. We found that Dih molecules mostly bind to three different sites of the protofibril: the exterior central hydrophobic core (CHC) spanning residues 17LVFFA21 in the β1 region, the protofibril cavity and the C-terminal hydrophobic-groove spanning residues 31IIGLM35 in the β2 region. Binding to the C-terminal hydrophobic-groove slightly affects the structures of Aβ17-42 protofibrils, while binding to the exterior CHC and the cavity strongly destabilizes the protofibrils by mostly disrupting the D23-K28 salt bridges and the inter-peptide β-sheet in the β1 region. The dynamic process of Dih molecules entering the cavity of Aβ17-42 protofibrils is also investigated. We also examined the effect of Dih molecules on both U-shaped Aβ40/Aβ42 protofibrils and S-shaped Aβ42 protofibrils by carrying out multiple MD simulations. Our simulations show that Dih molecules can destabilize both U-shaped and S-shaped Aβ protofibrils by binding to the protofibril cavity. This study reveals the mechanism by which Dih molecules disrupt Aβ protofibrils, which may offer new clues for the development of drug candidates for the treatment of AD.