Anisotropic Spectroscopy and Electrical Properties of 2D ReS Se Alloys with Distorted 1T Structure.

2D black phosphorus (BP) and rhenium dichalcogenides (ReX , X = S, Se) possess intrinsic in-plane anisotropic physical properties arising from their low crystal lattice symmetry, which has inspired their novel applications in electronics, photonics, and optoelectronics. Different from BP with poor environmental stability, ReX has low-symmetry distorted 1T structures with excellent stability. In ReX , the electronic structure is weakly dependent on layer numbers, which restricts their property tunability and device applications.

Correction: Composition-dependent Raman modes of MoWS monolayer alloys.

Correction for 'Composition-dependent Raman modes of MoWS monolayer alloys' by Yanfeng Chen et al., Nanoscale, 2014, 6, 2833-2839.

Temperature-dependent photoluminescence emission and Raman scattering from Mo1-x W x S2 monolayers.

2D transition metal dichalcogenide (TMD) alloys with tunable band gaps have recently gained wide interest due to their potential applications in future nanoelectronics and optoelectronics. Here, we report the temperature-dependent photoluminescence (PL) and Raman spectra of Mo1-x W x S2 monolayers with W composition x = 0, 0.29, 0.

Evolution of the Valley Position in Bulk Transition-Metal Chalcogenides and Their Monolayer Limit.

Layered transition metal chalcogenides with large spin orbit coupling have recently sparked much interest due to their potential applications for electronic, optoelectronic, spintronics, and valleytronics. However, most current understanding of the electronic structure near band valleys in momentum space is based on either theoretical investigations or optical measurements, leaving the detailed band structure elusive. For example, the exact position of the conduction band valley of bulk MoS2 remains controversial.

Photoconductivities in MoS2 Nanoflake Photoconductors.

Photoconductivities in molybdenum disulfide (MoS2) layered nanostructures with two-hexagonal crystalline structure prepared by mechanical exfoliation were investigated. The photoconductor-type MoS2 nanoflakes exhibit remarkable photoresponse under the above bandgap excitation wavelength of 532 nm at different optical intensity. The photocurrent responsivity and photoconductive gain of nanoflakes can reach, respectively, 30 AW(-1) and 103 at the intensity of 50 Wm(-2), which are several orders of magnitude higher than those of their bulk counterparts.

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures.

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed.

Single-Layer ReS₂: Two-Dimensional Semiconductor with Tunable In-Plane Anisotropy.

Rhenium disulfide (ReS2) and diselenide (ReSe2), the group 7 transition metal dichalcogenides (TMDs), are known to have a layered atomic structure showing an in-plane motif of diamond-shaped-chains (DS-chains) arranged in parallel. Using a combination of transmission electron microscopy and transport measurements, we demonstrate here the direct correlation of electron transport anisotropy in single-layered ReS2 with the atomic orientation of the DS-chains, as also supported by our density functional theory calculations. We further show that the direction of conducting channels in ReS2 and ReSe2 can be controlled by electron beam irradiation at elevated temperatures and follows the strain induced to the sample.

The interactome of soybean GmWRKY53 using yeast 2-hybrid library screening to saturation.

Soybean GmWRKY53 functions in both biotic and abiotic stress signaling. Using GmWRKY53 as a bait yeast 2-hybrid library screening to saturation isolated multiple independent fragments for many interacting proteins, enabling delineation of minimal interacting domains and computation of a confidence score. Multiple independent clones coding for the LATE ELONGATED HYPOCOTYL clock protein GmLCL2 (MYB114) were isolated and the binding site for GmWRKY53 was mapped to 90 amino acids separate from the MYB domain.

Integrated digital inverters based on two-dimensional anisotropic ReS2 field-effect transistors.

Semiconducting two-dimensional transition metal dichalcogenides are emerging as top candidates for post-silicon electronics. While most of them exhibit isotropic behaviour, lowering the lattice symmetry could induce anisotropic properties, which are both scientifically interesting and potentially useful. Here we present atomically thin rhenium disulfide (ReS2) flakes with unique distorted 1T structure, which exhibit in-plane anisotropic properties.

Three-fold rotational defects in two-dimensional transition metal dichalcogenides.

As defects frequently govern the properties of crystalline solids, the precise microscopic knowledge of defect atomic structure is of fundamental importance. We report a new class of point defects in single-layer transition metal dichalcogenides that can be created through 60° rotations of metal-chalcogen bonds in the trigonal prismatic lattice, with the simplest among them being a three-fold symmetric trefoil-like defect. The defects, which are inherently related to the crystal symmetry of transition metal dichalcogenides, can expand through sequential bond rotations, as evident from in situ scanning transmission electron microscopy experiments, and eventually form larger linear defects consisting of aligned 8-5-5-8 membered rings.

Effects of ion insertion on cycling performance of miniaturized electrochemical capacitor of carbon nanotubes array.

Capacity degradation and ion insertion of a miniaturized electrochemical capacitor are studied using ionic liquid [EMI] [TFSI] as the electrolyte. This capacitor is featured with two comb-like electrodes of vertical carbon nanotubes, ∼70 μm in height and 20 μm in interelectrode gap. We quantify the levels of ion insertion damage with Raman spectroscopy after the electrode experiences 120 consecutive voltammetric cycles to various potential limits.

Thickness-dependent electrical conductivities and ohmic contacts in transition metal dichalcogenides multilayers.

We report on the observation of the substantial thickness (t)-dependent electrical conductivity (σ) at a wide thickness range for an MoSe₂ layer semiconductor. The conductivity increases for more than two orders of magnitude from 4.6 to 1500 Ω(-1) cm(-1) with a decrease in thickness from 2700 to 6 nm.

Electrical transport properties of single-layer WS2.

We report on the fabrication of field-effect transistors based on single layers and bilayers of the semiconductor WS2 and the investigation of their electronic transport properties. We find that the doping level strongly depends on the device environment and that long in situ annealing drastically improves the contact transparency, allowing four-terminal measurements to be performed and the pristine properties of the material to be recovered. Our devices show n-type behavior with a high room-temperature on/off current ratio of ∼10(6).

Two-dimensional molybdenum tungsten diselenide alloys: photoluminescence, Raman scattering, and electrical transport.

Two-dimensional transition-metal dichalcogenide alloys have attracted intense attention due to their tunable band gaps. In the present work, photoluminescence, Raman scattering, and electrical transport properties of monolayer and few-layer molybdenum tungsten diselenide alloys (Mo1-xWxSe2, 0 ≤ x ≤ 1) are systematically investigated. The strong photoluminescence emissions from Mo1-xWxSe2 monolayers indicate composition-tunable direct band gaps (from 1.

Atomic mechanism of the semiconducting-to-metallic phase transition in single-layered MoS2.

Phase transitions can be used to alter the properties of a material without adding any additional atoms and are therefore of significant technological value. In a solid, phase transitions involve collective atomic displacements, but such atomic processes have so far only been investigated using macroscopic approaches. Here, we show that in situ scanning transmission electron microscopy can be used to follow the structural transformation between semiconducting (2H) and metallic (1T) phases in single-layered MoS2, with atomic resolution.

Properties of individual dopant atoms in single-layer MoS2: atomic structure, migration, and enhanced reactivity.

Single-layered MoS2 doped with Re (n-type) and Au (p-type) are investigated by in situ scanning transmission electron microscopy. Re atoms substituting Mo sites enhance the local chemical affinity, evidenced by agglomeration of other dopant/impurity atoms. Au atoms exist as adatoms and show larger mobility under the electron beam.

Monolayer behaviour in bulk ReS2 due to electronic and vibrational decoupling.

Semiconducting transition metal dichalcogenides consist of monolayers held together by weak forces where the layers are electronically and vibrationally coupled. Isolated monolayers show changes in electronic structure and lattice vibration energies, including a transition from indirect to direct bandgap. Here we present a new member of the family, rhenium disulphide (ReS2), where such variation is absent and bulk behaves as electronically and vibrationally decoupled monolayers stacked together.

Composition-dependent Raman modes of Mo(1-x)W(x)S2 monolayer alloys.

Two-dimensional (2D) transition-metal dichalcogenide alloys with tunable band gaps have promising applications in nanoelectronics and optoelectronics. Characterization of structures of 2D alloys, such as composition and atom mixing, is of fundamental importance to their applications. Here, we have conducted systematic Raman spectroscopic studies on Mo1-xWxS2 monolayers (0 ≤x≤ 1).

Cycle stability of the electrochemical capacitors patterned with vertically aligned carbon nanotubes in an LiPF6-based electrolyte.

The miniature ultracapacitors, with interdigitated electrodes of vertically aligned carbon nanotubes (VACNTs) and an inter-electrode gap of 20 μm, have been prepared in the LiPF6 organic electrolyte with and without PVdF-HFP gel. PVdF-HFP between two opposing electrodes enhances the device reliability, but lessens its power performance because of the extra diffusion resistance. Also noteworthy are the gel influences on the cycle stability.

The study of optical band edge property of bismuth oxide nanowires α-Bi2O3.

The α-phase Bi(2)O(3) (α-Bi(2)O(3)) is a crucial and potential visiblelight photocatalyst material needless of intentional doping on accommodating band gap. The understanding on fundamental optical property of α-Bi(2)O(3) is important for its extended applications. In this study, bismuth oxide nanowires with diameters from tens to hundreds nm have been grown by vapor transport method driven with vapor-liquid-solid mechanism on Si substrate.

Tunable band gap photoluminescence from atomically thin transition-metal dichalcogenide alloys.

Band gap engineering of atomically thin two-dimensional (2D) materials is the key to their applications in nanoelectronics, optoelectronics, and photonics. Here, for the first time, we demonstrate that in the 2D system, by alloying two materials with different band gaps (MoS2 and WS2), tunable band gap can be obtained in the 2D alloys (Mo(1-x)W(x)S(2) monolayers, x = 0-1). Atomic-resolution scanning transmission electron microscopy has revealed random arrangement of Mo and W atoms in the Mo(1-x)W(x)S(2) monolayer alloys.

Surface oxide effect on optical sensing and photoelectric conversion of α-In2Se3 hexagonal microplates.

The surface formation oxide assists of visible to ultraviolet photoelectric conversion in α-In2Se3 hexagonal microplates has been explored. Hexagonal α-In2Se3 microplates with the sizes of 10s to 100s of micrometers were synthesized and prepared by the chemical vapor transport method using ICl3 as a transport agent. Many vacancies and surface imperfection states have been found in the bulk and on the surface of the microplate because of the intrinsic defect nature of α-In2Se3.

Visualization and quantification of transition metal atomic mixing in Mo1-xWxS2 single layers.

The alloying behaviour of materials is a well-known problem in all kinds of compounds. Revealing the heteroatomic distributions in two-dimensional crystals is particularly critical for their practical use as nano-devices. Here we obtain statistics of the homo- and heteroatomic coordinates in single-layered Mo(1-x)W(x)S(2) from the atomically resolved scanning transmission electron microscope images and successfully quantify the degree of alloying for the transition metal elements (Mo or W).

Allelic differences in Medicago truncatula NIP/LATD mutants correlate with their encoded proteins' transport activities in planta.

Medicago truncatula NIP/LATD gene, required for symbiotic nitrogen fixing nodule and root architecture development, encodes a member of the NRT1(PTR) family that demonstrates high-affinity nitrate transport in Xenopus laevis oocytes. Of three Mtnip/latd mutant proteins, one retains high-affinity nitrate transport in oocytes, while the other two are nitrate-transport defective. To further examine the mutant proteins' transport properties, the missense Mtnip/latd alleles were expressed in Arabidopsis thaliana chl1-5, resistant to the herbicide chlorate because of a deletion spanning the nitrate transporter AtNRT1.

Miniature asymmetric ultracapacitor of patterned carbon nanotubes and hydrous ruthenium dioxide.

A symmetric ultracapacitor CNT_CNT and an asymmetric ultracapacitor CNT_hRuO(2) of mini size have been prepared with patterned carbon nanotubes (CNT) and hydrous ruthenium dioxide. Galvanostatic charge/discharge results indicate that CNT_hRuO(2) is the superior one in both power and energy densities. In a potential window 2.