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81.
目的 建立刚性微球与织构化涂层表面黏附接触数值分析模型,探究织构化涂层属性对微观接触副黏附力学性能的影响。方法 基于Hamaker求和法以及Lennard–Jones势能定律,考虑织构高度对接触体间距离分布的影响以及涂层、织构材料属性对接触体间黏附力的影响,建立织构化涂层表面黏附接触力学模型并验证所提模型。基于所提模型,研究不同Tabor数下织构形貌、密度、高度以及涂层厚度对接触系统黏附力学性能的影响。结果 在相同参数下,圆柱型织构黏附力最大,半椭球型织构次之,四棱锥型织构最小。织构密度从200μm-2增加到4 000μm-2时,最大黏附力随着织构密度的增加而增加,圆柱型织构增加约5~6倍,四棱锥型织构增加约1.5倍。随着织构高度从1εbs增加至30εbs,最大黏附力减小,四棱锥型织构减小最多,约为原来的1%,圆柱形织构减小最少,约为原来的90%。涂层厚度能够影响黏附力的大小,但影响规律与织构化涂层的Tabor数及织构高度相关。随着涂层厚度从1εbs增加至16εbs,大Tabo... 相似文献
82.
Vanadium Diselenide Single Crystals: Van der Waals Epitaxial Growth of 2D Metallic Vanadium Diselenide Single Crystals and their Extra‐High Electrical Conductivity (Adv. Mater. 37/2017)
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83.
Electric Field Tunable Interlayer Relaxation Process and Interlayer Coupling in WSe2/Graphene Heterostructures
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Yang Li Jing‐Kai Qin Cheng‐Yan Xu Jian Cao Zhao‐Yuan Sun Lai‐Peng Ma Ping An Hu Wencai Ren Liang Zhen 《Advanced functional materials》2016,26(24):4319-4328
Transition metal dichalcogenides van der Waals (vdWs) heterostructures present fascinating optical and electronic phenomena, and bear tremendous significance for electronic and optoelectronic applications. As the significant merits in vdWs heterostructures, the interlayer relaxation of excitons and interlayer coupling at the heterointerface reflect the dynamic behavior of charge transfer and the coupled electronic/structural characteristics, respectively, which may give rise to new physics induced by quantum coupling. In this work, upon tuning the photoluminescence (PL) properties of WSe2/graphene and WSe2/MoS2/graphene heterostructures by virtue of electric field, it is demonstrated that the interlayer relaxation of excitons at the heterointerface in WSe2/graphene, which is even stronger than that in MoS2/graphene and WSe2/MoS2 , plays a dominant role in PL tuning in WSe2/graphene, while the carrier population in WSe2 induced by electric field has a minor contribution. In addition, it is discovered that the interlayer coupling between monolayer WSe2 and graphene is enhanced under high electric field, which breaks the momentum conservation of first order Raman‐allowed phonons in graphene, yielding the enhanced Raman scattering of defects in graphene. The interplay between electric field and vdWs heterostructures may provide versatile approaches to tune the intrinsic electronic and optical properties of the heterostructures. 相似文献
84.
Epitaxy of Layered Orthorhombic SnS–SnSxSe(1−x) Core–Shell Heterostructures with Anisotropic Photoresponse
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Jing Xia Dandan Zhu Xuanze Li Lei Wang Lifeng Tian Jing Li Jingyuan Wang Xing Huang Xiang‐Min Meng 《Advanced functional materials》2016,26(26):4673-4679
Vertical and in‐plane heterostructures based on van der Waals (vdW) crystals have drawn rapidly increasing attention owning to the extraordinary properties and significant application potential. However, current heterostructures are mainly limited to vdW crystals with a symmetrical hexagonal lattice, and the heterostructures made by asymmetric vdW crystals are rarely investigated at the moment. In this contribution, it is reported for the first time the synthesis of layered orthorhombic SnS–SnSxSe(1?x) core–shell heterostructures with well‐defined geometry via a two‐step thermal evaporation method. Structural characterization reveals that the heterostructures of SnS–SnSxSe(1?x) are in‐plane interconnected and vertically stacked, constructed by SnSxSe(1?x) shell heteroepitaxially growing on/around the pre‐synthesized SnS flake with an epitaxial relationship of (303)SnS//(033)SnSxSe(1?x), [010]SnS//[100]SnSxSe(1?x). On the basis of detailed morphology, structure and composition characterizations, a growth mechanism involving heteroepitaxial growth, atomic diffusion, as well as thermal thinning is proposed to illustrate the formation process of the heterostructures. In addition, a strong polarization‐dependent photoresponse is found on the device fabricated using the as‐prepared SnS?SnSxSe(1?x) core–shell heterostructure, enabling the potential use of the heterostructures as functional components for optoelectronic devices featured with anisotropy. 相似文献
85.
86.
Yazeed Alaskar Shamsul Arafin Darshana Wickramaratne Mark A. Zurbuchen Liang He Jeff McKay Qiyin Lin Mark S. Goorsky Roger K. Lake Kang L. Wang 《Advanced functional materials》2014,24(42):6629-6638
Van der Waals growth of GaAs on silicon using a two‐dimensional layered material, graphene, as a lattice mismatch/thermal expansion coefficient mismatch relieving buffer layer is presented. Two‐dimensional growth of GaAs thin films on graphene is a potential route towards heteroepitaxial integration of GaAs on silicon in the developing field of silicon photonics. Hetero‐layered GaAs is deposited by molecular beam epitaxy on graphene/silicon at growth temperatures ranging from 350 °C to 600 °C under a constant arsenic flux. Samples are characterized by plan‐view scanning electron microscopy, atomic force microscopy, Raman microscopy, and X‐ray diffraction. The low energy of the graphene surface and the GaAs/graphene interface is overcome through an optimized growth technique to obtain an atomically smooth low temperature GaAs nucleation layer. However, the low adsorption and migration energies of gallium and arsenic atoms on graphene result in cluster‐growth mode during crystallization of GaAs films at an elevated temperature. In this paper, we present the first example of an ultrasmooth morphology for GaAs films with a strong (111) oriented fiber‐texture on graphene/silicon using quasi van der Waals epitaxy, making it a remarkable step towards an eventual demonstration of the epitaxial growth of GaAs by this approach for heterogeneous integration. 相似文献
87.
Jake D. Mehew Selim Unal Elias Torres Alonso Gareth F. Jones Saad Fadhil Ramadhan Monica F. Craciun Saverio Russo 《Advanced materials (Deerfield Beach, Fla.)》2017,29(23)
The combination of graphene with semiconductor materials in heterostructure photodetectors enables amplified detection of femtowatt light signals using micrometer‐scale electronic devices. Presently, long‐lived charge traps limit the speed of such detectors, and impractical strategies, e.g., the use of large gate‐voltage pulses, have been employed to achieve bandwidths suitable for applications such as video‐frame‐rate imaging. Here, atomically thin graphene–WS2 heterostructure photodetectors encapsulated in an ionic polymer are reported, which are uniquely able to operate at bandwidths up to 1.5 kHz whilst maintaining internal gain as large as 106. Highly mobile ions and the nanometer‐scale Debye length of the ionic polymer are used to screen charge traps and tune the Fermi level of the graphene over an unprecedented range at the interface with WS2. Responsivity R = 106 A W?1 and detectivity D* = 3.8 × 1011 Jones are observed, approaching that of single‐photon counters. The combination of both high responsivity and fast response times makes these photodetectors suitable for video‐frame‐rate imaging applications. 相似文献
88.
Xiao Yan Chunsen Liu Chao Li Wenzhong Bao Shijin Ding David Wei Zhang Peng Zhou 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(34)
The burgeoning 2D semiconductors can maintain excellent device electrostatics with an ultranarrow channel length and can realize tunneling by electrostatic gating to avoid deprivation of band‐edge sharpness resulting from chemical doping, which make them perfect candidates for tunneling field effect transistors. Here this study presents SnSe2/WSe2 van der Waals heterostructures with SnSe2 as the p‐layer and WSe2 as the n‐layer. The energy band alignment changes from a staggered gap band offset (type‐II) to a broken gap (type‐III) when changing the negative back‐gate voltage to positive, resulting in the device operating as a rectifier diode (rectification ratio ~104) or an n‐type tunneling field effect transistor, respectively. A steep average subthreshold swing of 80 mV dec?1 for exceeding two decades of drain current with a minimum of 37 mV dec?1 at room temperature is observed, and an evident trend toward negative differential resistance is also accomplished for the tunneling field effect transistor due to the high gate efficiency of 0.36 for single gate devices. The I ON/I OFF ratio of the transfer characteristics is >106, accompanying a high ON current >10?5 A. This work presents original phenomena of multilayer 2D van der Waals heterostructures which can be applied to low‐power consumption devices. 相似文献
89.
目的 通过分析纸塑复合袋成型工艺,针对纸塑复合袋生产中存在位置偏移和倾斜的缺陷,明确复合袋生产中需要纠偏的需求.方法 建立复合袋的有限元模型,以薄板屈曲理论为基础,运用Ansys Workbench中的屈曲分析工具对各种姿态下的纸塑复合袋进行仿真,求解皮带最大屈曲载荷,最后根据最大屈曲载荷等于复合袋所受的摩擦力这一条件,得到皮带所受的最大正压力.结果 当皮带间距为50 cm时,最大皮带正压力最大,即纸塑复合袋能够承受的摩擦力最大,纠偏时的轨迹与理论轨迹误差更小.结论 该计算结果准确,数据充足,满足纠偏中正压力的控制需求. 相似文献
90.