Electron Release via Internal Polarization Fields for Optimal S-H Bonding States.

Transition metal dichalcogenides (TMDs) have received considerable attention as promising electrocatalysts for the hydrogen evolution reaction (HER), yet their potential is often constrained by the inertness of the basal planes arising from their poor hydrogen adsorption ability. Here, the relationship between the electronic structure of the WS basal plane and HER activity is systemically analyzed to establish a clear insight. The valance state of the sulfur atoms on the basal plane has been tuned to enhance hydrogen adsorption through sequential engineering processes, including direct phase transition and heterostructure that induces work function-difference-induced unidirectional electron transfer.

Low-Temperature, Universal Synthetic Route for Mesoporous Metal Oxides by Exploiting Synergistic Effect of Thermal Activation and Plasma.

Mesoporous metal oxides exhibit excellent physicochemical properties and are widely used in various fields, including energy storage/conversion, catalysis, and sensors. Although several soft-template approaches are reported, high-temperature calcination for both metal oxide formation and template removal is necessary, which limits direct synthesis on a plastic substrate for flexible devices. Here, a universal synthetic approach that combines thermal activation and oxygen plasma to synthesize diverse mesoporous metal oxides (VO, VO, TiO, NbO, WO and MoO) at low temperatures (150-200 °C), which can be applicable to a flexible polymeric substrate is introduced.

Selective Laser-Assisted Direct Synthesis of MoS for Graphene/MoS Schottky Junction.

Implementing a heterostructure by vertically stacking two-dimensional semiconductors is necessary for responding to various requirements in the future of semiconductor technology. However, the chemical-vapor deposition method, which is an existing two-dimensional (2D) material-processing method, inevitably causes heat damage to surrounding materials essential for functionality because of its high synthesis temperature. Therefore, the heterojunction of a 2D material that directly synthesized MoS on graphene using a laser-based photothermal reaction at room temperature was studied.

Effect of Measurement System Configuration and Operating Conditions on 2D Material-Based Gas Sensor Sensitivity.

Gas sensors applied in real-time detection of toxic gas leakage, air pollution, and respiration patterns require a reliable test platform to evaluate their characteristics, such as sensitivity and detection limits. However, securing reliable characteristics of a gas sensor is difficult, owing to the structural difference between the gas sensor measurement platform and the difference in measurement methods. This study investigates the effect of measurement conditions and system configurations on the sensitivity of two-dimensional (2D) material-based gas sensors.

S/Mo ratio and petal size controlled MoS nanoflowers with low temperature metal organic chemical vapor deposition and their application in solar cells.

Vertically aligned two-dimensional (2D) molybdenum disulfide nanoflowers (MoS NFs) have drawn considerable attention as a novel functional material with potential for next-generation applications owing to their inherently distinctive structure and extraordinary properties. We report a simple metal organic chemical vapor deposition (MOCVD) method that can grow high crystal quality, large-scale and highly homogeneous MoS NFs through precisely controlling the partial pressure ratio of HS reaction gas, P , to Mo(CO) precursor, P , at a substrate temperature of 250 °C. We investigate microscopically and spectroscopically that the S/Mo ratio, optical properties and orientation of the grown MoS NFs can be controlled by adjusting the partial pressure ratio, P /P .

Development of in-situ particle monitor with beam homogenizing module for enhancement of nanoparticle countering efficiency.

An in situ particle monitor (ISPM) was developed to measure the concentration of several hundred nanosized contaminant particles generated from the semiconductor process. It is difficult to measure particles below 300 nm owing to low sensitivity and reliability. To improve the sensitivity and reduce the uncertainty caused by the Gaussian distribution of laser, a beam homogenizing module was applied to transform the Gaussian beam into a flat-top beam by total internal reflection.

Unsupervised Learning for Depth, Ego-Motion, and Optical Flow Estimation Using Coupled Consistency Conditions.

Herein, we propose an unsupervised learning architecture under coupled consistency conditions to estimate the depth, ego-motion, and optical flow. Previously invented learning techniques in computer vision adopted a large amount of the ground truth dataset for network training. A ground truth dataset, including depth and optical flow collected from the real world, requires tremendous effort in pre-processing due to the exposure to noise artifacts.

Highly sensitive two-dimensional MoS gas sensor decorated with Pt nanoparticles.

A two-dimensional molybdenum disulfide (MoS)-based gas sensor was decorated with Pt nanoparticles (NPs) for high sensitivity and low limit of detection (LOD) for specific gases (NH and HS). The two-dimensional MoS film was grown at 400°C using metal organic gas vapour deposition. To fabricate the MoS gas sensor, an interdigitated Au/Ti electrode was deposited using the electron beam (e-beam) evaporation method with a stencil mask.

Observation of photoluminescence from large-scale layer-controlled 2D ß-CuS synthesized by the vapor-phase sulfurization of copper thin films.

Two-dimensional (2D) copper chalcogenides (Cu X where X = S, Se, Te) have had much attention regarding various applications due to their remarkable optical and electrical properties, abundance, and environmentally friendly natures. This work indicates that highly uniform Cu S (where 0 < x < 1) nanosheets can be obtained by the two-step method of Cu deposition by sputtering with precisely controlled and extremely low growth rate followed by vapor-phase sulfurization. The phase transformations of thin Cu S films upon the Cu seed layer thickness are investigated.

Wafer-scale production of highly uniform two-dimensional MoS by metal-organic chemical vapor deposition.

Semiconducting two-dimensional (2D) materials, particularly extremely thin molybdenum disulfide (MoS) films, are attracting considerable attention from academia and industry owing to their distinctive optical and electrical properties. Here, we present the direct growth of a MoS monolayer with unprecedented spatial and structural uniformity across an entire 8 inch SiO/Si wafer. The influences of growth pressure, ambient gases (Ar, H), and S/Mo molar flow ratio on the MoS layered growth were explored by considering the domain size, nucleation sites, morphology, and impurity incorporation.

Hierarchical, Dual-Scale Structures of Atomically Thin MoS for Tunable Wetting.

Molybdenum disulfide (MoS), a well-known solid lubricant for low friction surface coatings, has recently drawn attention as an analogue two-dimensional (2D) material beyond graphene. When patterned to produce vertically grown, nanoflower-structures, MoS shows promise as a functional material for hydrogen evolution catalysis systems, electrodes for alkali metal-ion batteries, and field-emission arrays. Whereas the wettability of graphene has been substantially investigated, that of MoS structures, especially nanoflowers, has remained relatively unexplored despite MoS nanoflower's potential in future applications.

Development of particle characteristics diagnosis system for nanoparticle analysis in vacuum.

A particle characteristics diagnosis system (PCDS) was developed to measure nano-sized particle properties by a combination of particle beam mass spectrometry, scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS). It allows us to measure the size distributions of nano-sized particles in real time, and the shape and composition can be determined by in situ SEM imaging and EDS scanning. PCDS was calibrated by measuring the size-classified nano-sized NaCl particles generated using an aqueous solution of NaCl by an atomizer.

Low-temperature growth of layered molybdenum disulphide with controlled clusters.

Layered molybdenum disulphide was grown at a low-temperature of 350 °C using chemical vapour deposition by elaborately controlling the cluster size. The molybdenum disulphide grown under various sulphur-reaction-gas to molybdenum-precursor partial-pressure ratios were examined. Using spectroscopy and microscopy, the effect of the cluster size on the layered growth was investigated in terms of the morphology, grain size, and impurity incorporation.

Theoretical analysis for quantitative evaluation of in-situ nanoparticle measurement probability.

A probability equation based on the proper assumptions of the particle trajectory and fundamental physics has been developed by analyze beam properties such as beam width and intensity distribution for an in situ particle monitor (ISPM). The radius coordinate which has the same intensity and portion of beam area for detection voltage range were analyzed to calculate particle measurement probability. The particle measurement probability is defined at a ratio of entire beam area to specified beam area which decided by detection voltage range.

Histopathological pictures of the initial changes of the hair bulbs in alopecia areata.

A biopsy of the seemingly normal scalp of a patient who had just begun to develop alopecia areata showed distinctive changes in bulbar morphology, in addition to peribulbar lymphocytic infiltrates. One of these changes was a loss of structural integrity of the centrally located supramatrical upper bulbar region. The other was the shrinkage of hair bulbs in the direction of club shape.