【作者】 王微；

【导师】 付德君；

【作者基本信息】 武汉大学 ， 粒子物理与原子核物理， 2016， 博士

【摘要】 随着纳米科学技术的发展,作为新一代电子和光电器件的层状结构的二维材料得到广泛关注和研究。例如石墨烯(Graphene, Gr)和过渡金属硫化物(TMDs)。然而,由于无带隙造成的低的电流开关率使得石墨烯在逻辑电子器件方面的应用被限制。过渡金属硫化物,特别是MoS2作为新兴半导体类石墨烯材料和独特的性能吸引各界研究人员的广泛关注。本论文首先对MoS2研究现状进行概述；之后简介本论文中涉及到的MoS2的制备方法以及表征方法；然后详细介绍水热法制备的MoS2以及超声震荡辅助水热法制备的MoS2/reduced Graphene Oxide (MoS2/rG0)纳米复合材料的晶体结构。最后重点研究Au/MoS2(纳米球)／Au结构的光电性能。具体分为以下几个方面：一、水热法制备MoS2以及超声震荡辅助的水热法制备MoS2/rG0纳米复合材料。以Na2MoO, ·2H.0和TAA (CH3CSNH2)为前驱体,在高温高压下发生水热反应制备三维类球体结构的MoS2；之后通过有计划地加入不同比率的类石墨烯(Gr)结构的胶状氧化石墨烯(GO)纳米片,并以超声震荡为辅助技术,优化MoS2的生长——在适当比率下得到1～2层MoS2晶体——形成自组装的低维层状MoS2/rG0纳米复合结构材料；并进一步提出低维层状MoS2/rGO纳米复合结构的原位自组装生长机理。GO还原程度的可控性操作将会在MoS2或者rG0(或者Gr)材料中形成具有电子量子限域效应的结构使该纳米复合材料具有广阔的应用前景。二、Au/MoS2(纳米球)/Au结构光电性能研究。在黑暗中或者白光激发情况下,基于不同极化电压,对MoS2纳米球的光敏忆阻器光电性能进行研究。具有平面Au电极结构的MoS2纳米球光敏忆阻器表现出光敏阻变特性。该新颖器件被纳米球的极化(率)所调制——在黑暗或者白光激发下,电场中纳米球的极化(率)引起阻变现象。极化电荷允许改变光敏忆阻器的开关电压使该忆阻器具有多阶操作。在极化电压6V时,MoS2纳米球的光敏忆阻器在黑暗中显示出平滑的阻变特性；然而,白光激发下(光谱最大能量范围2.7 eV—1.8 eV)该光敏忆阻器在-2.9 V突然从HRS/OFF态转变到LRS/ON态——SET操作——代表忆阻器器件中“写入”程序；4.2 V突然从低组态(LRS, ON态)转变到高组态(HRS, OFF态)——RESET操作——代表忆阻器器件中“擦除”程序；并且ON/OFF电流比为～10；并通过分析该光敏忆阻器在不同电阻态的电导率来阐明电阻转换特性的传导机制——在黑暗或者白光激发下,电场中的电荷形成／中断具有高导电性的灯丝纤维调制电阻态。另外,该新颖结构显示可重写的非易失性电阻开关特性并在多周期(1000)之后仍然表现出良好的机械耐力。利用简便廉价的方法制备的该光敏忆阻器具有作为新的多功能器件的巨大潜力。另外,由于极化过程比离子漂移快得多,所以在外电场作用下通过光辐照操作致使电子注入的过程来调制极化的纳米球界面上的势垒高度在基于纳米球的高速器件中是相当有远景的。更多还原

【Abstract】 With the development of nanometer science and technology, layered structure of two-dimensional material such as Graphene (Gr) and transitional metal dichalcogenides (TMDs), have attracted widely attention. However, the low rate of current switching caused by no band gap makes graphene limited in logic electronics applications. Transitional metal dichalcogenides, especially MoS2, as a semiconducting analogue of Gr and unique properties have attracted the attention of the researchers. This paper firstly introduces a overview of MoS2. After the introducing basic properties of MoS2, we study MoS2 and MoS2/rGO nanocomposites by hydrothermal method. Finally it focuses on Au/MoS2 (nanospheres)/Au structure photoelectric properties. Contents is divided into the following several aspects:1、Synthesis MoS2 by hydrothermal method and self-assembled low-dimensional MoS2/rGO composites by sonication-assisted hydrothermal growthThe self-assembled low-dimensional MoS2/rGO composites were synthesized by the one-step hydrothermal procedure in liquid phase with Na2MoO4·2H2O and CH3CSNH2 using as precursors. The results indicate that rGO, derived from the deoxygenation of GO provides an excellent template for the growth of low-dimensional (1-2 layer) MoS2 in the form of 2D crystal or 3D nanosphere. The mechanism of self-assembled MoS2/rGO was proposed. The quantum confinement of electrons in a molybdenum disulfide or graphene controlled by the degree of reduction of graphene oxide gives great features to apply in advanced photonics and optoelectronics.2、MoS2 memristor with photoresistive switchingMoS2 nanosphere memristor with lateral gold electrodes was found to show a photoresistive switching. The novel device can be controlled by a charge polarization of the nanospheres and switched the resistance by an electric field in the dark and under white light illumination. The charge polarization allows to change the switching voltage of the photomemristor, providing the multi-level operation. The nanosphere structure polarized at voltage of 6V shows the sharp resistive switching under white light excitation from high resistance state (HRSL6) to low resistance state (LRSL6) with ON/OFF ratio of 10. Analysis of the electrical conductivity in the resistive states indicates that charging and polarization the nanospheres modulated by light could form and interrupt highly conductive filaments to switch the photoresistance. MoS2 photomemristor shows great potential as a new multifunctional device, obtained by simple solution-processing techniques.更多还原