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Two-dimensional (2D) graphene has shown great potential of breakthrough of Moore's law limitation due to its atomic thickness in electronic devices. Up to now, chemical vapor deposition (CVD) is a widely applied method for graphene growth due to its low-cost, large-area production, and easy control in layer number. However, the CVD-grown graphene usually suffers from relatively low quality derived from the polycrystalline nature of catalytic metal (e. g., Cu) substrates. Herein, single-crystal Cu (111) substrates were fabricated by a high-temperature annealing process, initial nucleation of graphene on it has been well controlled, and high-quality and centimeter-size single-crystal graphene was achieved. The Cu (111) substrate provides onefold orientation for the graphene growth according to their lattice matching relation, and domain boundaries of neighboring graphene nuclei could stitch together. The as-grown single-crystal graphene has an average sheet resistance of 607. 5 Ω · sq-1. Compared to that of grown on the pristine polycrystalline Cu (1 415. 7 Ω · sq -1), it shows high electrical conductivity. High-temperature annealing purified the Cu foils, and induced a clean graphene surface with lower roughness. The quality of graphene is further verified by using it in a field-effect transistor (FET), resulting in a maximum switch ratio of 145. 5 and carrier mobility of 2. 31 x 10³ cm² · V-1 · s-1. Based on these results, we believe that the single-crystal graphene in present work is also feasible for fabricating other high-performance electronic devices. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Molecular Science is the property of Journal of Molecular Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

5G communication, energy internet, new energy automobiles, quantum technology and other advanced and sophisticated fields have put forward new and higher requirements for the performance of semiconductors. The fourth generation of semiconductor diamond is known as the “ultimate semiconductor” because of its excellent physical and chemical properties. It is considered to be the most ideal material for developing the next generation of high power, high frequency, high temperature and low power loss electronic devices. However, the technical bottleneck of shallow n-type doping has hindered the development of diamond semiconductor applications to a certain extent. The research of surface terminals has provided new strategies for the development of diamond functionalization. Diamond has realized important applications such as field effect transistors, Schottky diodes, solar-blind ultraviolet detectors, electronic emission devices and near-surface color center tuning through surface terminals. The mechanism of surface terminals exerting effects is inseparable from the characteristics of their energy band structure. In this paper, the research methods of energy band structure of several common terminals are summarized, the characteristics of their energy band structures are analyzed, the mechanism of exerting effects in combination with the characteristics are introduced, finally prospected. [ABSTRACT FROM AUTHOR]

Compared with traditional silicon materials, wide-band gap semiconductors are more suitable for making high voltage, high-frequency and high-power semiconductor devices, and are considered to be the key role of material innovation in the post-Moore era. Single-crystal diamond (SCD) has superiorities of wide-band gap, extremely high thermal conductivity and high mobility, and is expected to develop high-power, high-frequency electronic devices. However, the limitation of SCD wafer size and ultra-expensive price obstructed its promotion. After a long-time exploration, heteroepitaxy technology is recognized as an effective approach to obtain high-quality and large-size SCD wafer. This review introduces the development of heteroepitaxial SCD in detail, in aspects of substrate selection, growth mechanism and quality improvement. Furthermore, the investigations of field-effect transistors and diodes based on heteroepitaxial SCD are summarized, indicating the great potential of heteroepitaxial SCD in electronic device field. Finally, the challenges of heteroepitaxial technology are pointed out, and the potential applications are anticipated. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tungsten disulfide (WS2 ) has a wide application prospect in the field of optoelectronic devices due to its properties such as tunable band gap, strong light-matter interaction and high carrier mobility and so on. Dendritic WS2 / monolayer WS2 was grown on SiO2 / Si substrate by atmospheric pressure chemical vapor deposition (CVD). Sulphur powder and transition metal oxides were used as precursors. The morphological evolution of the samples on the substrate was divided into four regions: superimposed growth region (Ⅳ), dendritic WS2 growth region (Ⅲ), hexagonal WS2 growth region (Ⅱ) and no obvious morphological region (Ⅰ). The differences in the number, morphology, structure and properties of the prepared dendritic WS2 / monolayer WS2 on the substrates were systematically compared by optical microscopy, atomic force microscopy, Raman spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, scanning electron microscopy and other testing methods. It is found that the morphology of the dendritic WS2 affects the actual defect concentration, thus affects the position of the Raman characteristic peaks. The growth mechanism of the morphological evolution was explained by the atomic adsorption model and the variation of the S and W vapor ratio. In addition, back-gated field effect transistor (FET) based on dendritic WS2 / monolayer WS2 homojunction with a responsivity of 46. 6 mA/ W is prepared, and its response and recovery time are in the microsecond range, showing its superior performances than the monolayer WS2 -FET prepared by CVD. This work will help to further understand the controlled growth of two-dimensional thin film materials and contribute to the preparation of large-area, high-quality dendrite structures. [ABSTRACT FROM AUTHOR]

Chemical vapor deposition (CVD) is an effective method for the growth of large scale two-dimensional materials. However, high density of vacancy defects are inevitably generated in the CVD process, which affects the photoelectric properties of the materials. In this work, millimeter-scale and atomic-thick WS2 membranes were directly grown on p-type Si (111) substrates using an alkali metal halide-assisted CVD method. Er-doped WS2 films ( WS2 ( Er)) were achieved by adding saturated ErCl 3 powders in the tungsten sources. Optical microscopy, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, photoluminescence and Raman spectroscopy techniques were used to characterize the materials systematically. The results show that the fluorescence intensity of WS2 (Er) films increase by an order of magnitude compared to pristine WS2, and the central wavelength is significantly redshifted. Fluorescence tests show that the fluorescence characteristics of WS2 grown on Si substrates show a significant charge transfer effect compared to that of WS2 on SiO2 substrates. The photoelectric test results of WS2 and WS2 (Er) field effect transistors based on SiO2 substrate show that the optical responsiveness of WS2 (Er) field effect transistors is 4. 015 A/ W, and the external quantum efficiency is 784%, both of which are more than 2 000 times that of pristine WS2 devices under the same conditions. This work has significance for research of rare earth doping in 2D materials. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Molybdenum disulfide (MoS2) has good thermal and chemical stability and relatively high mobility in the environment. It has been used in the applications of gas sensors, photodetectors and field effect transistors. Oxygen-doped molybdenum disulfide (MoS2-xOx) generated by oxygen-assisted technology can not only regulate the size of MoS2 single crystal, but also improve the photoluminescence intensity of MoS2 single crystal. MoS2-xOx films were prepared and their optical properties were investigated in this paper. First, radio frequency reactive magnetron sputtering technology was used to prepare the precursors of MoS2-xOx films; next, the precursors in natural environment for 60 d were oxidized; finally, the MoS2-xOx films after a thermal annealing process were obtained. Herein, the angle between the sputtering plume and the glass substrate was specifically varied. The optical properties of MoS2-xOx films were investigated. X-ray photoelectron spectroscopy was used to analyze the elements and valence states of the samples. Scanning electron microscopy results show that the surface morphology is optimal at an angle of 45° (θ=45°) between the sputtering plume and the substrate. UV-Vis spectrophotometry results show that the optical band gap of the MoS2-xOx films decreasing as the thickness and oxygen content increasing. COMSOL Multiphysics software was utilized to simulate the transmittance of MoS2-xOx films, and the theoretical and experimental results agree well. The results of this paper will provide experimental data reference for the application of MoS2-xOx in the field of optical devices. [ABSTRACT FROM AUTHOR]

Since the discovery of graphene in 2004, the research and application of two-dimensional (2D) materials have received great attention and developed rapidly. Abundant band gap structures, unique optoelectronic properties, and van der Waals surfaces without dangling bonds greatly broaden the design dimensions of semiconducting electronics and optoelectronics. Among them, the two-dimensional indium selenide, as one of the most promising candidates for future highmobility optoelectronic devices, it has been recognized as "the 'golden middle' between silicon and graphene" by Nobel Prize winner Andre Geim. However, the research on two-dimensional indium selenide material has only been less than ten years, and the understanding of crystals fabrication and device application is still insufficient. This work mostly focuses on the development of indium selenide materials and the research status of its electronic and optoelectronic devices. In addition, considering that the present research on 2D indium selenide are mostly based on mechanical exfoliation of InSe bulks, the development of the crystal structure characterization and crystals fabrication are traced in this paper, then the state-of-the-art on the preparation and performance characterization of two-dimensional indium selenide are further summarized, and the influence of device geometries, material fabrication method and other factors on the electrical transport performance of 2D indium selenide field effect transistors and photodetectors are further discussed, and ended with analysis of the opportunities and challenges for future indium selenide based applications. [ABSTRACT FROM AUTHOR]

Ion mobility (IM) coupled mass spectrometry (MS) is a versatile tool for analytical separations, characterization, and detection by measuring collision cross-sections and mass-to-charge (m/z) ratios. Traveling wave (TW)-based structures for lossless ion manipulations (TW-SLIM) is an innovative ion drift tube for complex gas phase ion manipulations, which is the key component of traveling wave ion mobility spectrometry (TWIMS). TW-SLIM combines flexible ion path design and traveling wave technology. The traveling wave pulse power supply is used to provide an oscillatory electric fields. Ions in TWIMS are propelled and separated by traveling wave. The operating pressure, TW amplitude and TW frequency of TW pulse have effect on ion motion in TWIMS. In this work, a traveling wave pulse power supply was developed, which mainly consisted of field programmable gate array (FPGA), half-bridge gate driver integrated circuit (IC), metal-oxide-semiconductor field effect transistor (MOSFET), adjustable high voltage module and external trigger signal. The frequency of TW pulse power supply was up to 100 kHz, both rising edge and falling edge were less than 20 ns. The influence of TW amplitude and TW frequency on ions transmission and separation was explored on the home-built instrument platform. The experimental results presented here provide a fundamental understanding of the transmission and separation mechanism in TWIMS. The maximum signal intensity of hexakis (2, 2-difluoroethoxy) phosphazene was at amplitude of 35 V and frequency of 10 kHz. As the traveling wave frequency increased at a fixed traveling wave amplitude, signal intensity of hexakis (2, 2-difluoroethoxy) phosphazene decreased. Ions separations was positively related to frequency when traveling wave amplitude was fixed, while traveling wave amplitude was opposite. The development of traveling wave pulse power supply is valuable for research and development of high resolution TWIMS instrument. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A library of π-conjugated systems have been developed through conventional tools of coupling (e.g. Suzuki coupling, Stille coupling) and have been used for the fabrication of organic optoelectronic devices. Herein, a facile, atomefficient and environmentally benign pathway is outlined, with water as the only by-product, for the synthesis of conjugated Schiff-based copolymers based on sulfur-heterocycle fused naphthalene diimides (NDIs) and aromatic diamines. These copolymers showed broad absorption spectra in the ultraviolet-visible (UV-Vis) region and low-lying LUMO levels at about −4.07 — −4.19 eV. The relationship between the chemical structure and the performance, including the optical properties, electrochemical properties, thermal stability, morphologies and the field-effect performance in transistors, is fully studied using these polymers as active layer. Compared with P1 and P2, P3 exhibits an absorption peak at 754 nm, with red shifts of 76 nm and 75 nm, respectively. An electron mobility of up to 2.47×10−3 cm2/ (V·s) can be achieved for P3-based transistors after performing a thermal annealing process at 300 ℃. The incorporation of rigid structure units into polymer conjugated skeleton can effectively tune its spectral absorption, energy level structure as well as the film morphology, thus improving the device performance. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Basic Sciences Journal of Textile Universities / Fangzhi Gaoxiao Jichu Kexue Xuebao is the property of Basic Sciences Journal of Textile Universities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)