二硫化钼二维材料及其异质结的制备和光电特性研究

发布时间：2018-03-08 23:01

本文选题：二维材料　切入点：二硫化钼　出处：《中国科学院研究生院(上海技术物理研究所)》2016年博士论文　论文类型：学位论文

【摘要】：过去的十几年来,石墨烯因优异的机械、光学、电学特性受到了极大的关注,且在光电子与微电子等领域的应用潜力巨大。近年来,过渡金属硫族化合物二维原子晶体材料展现了许多石墨烯所不具有的物理特性,广泛研究表明其在晶体管、光探测器、光伏电池等方面具有极大的应用前景。本论文面向过渡金属硫族化合物二维原子晶体材料的可控制备与范德瓦尔斯异质结,重点研究了二硫化钼二维原子晶体材料的气相生长与复合,以及基于单层二硫化钼原子晶体的二维范德瓦尔斯异质结的特性与应用。在以下几个方面取得了重要的阶段性进展:(1)类石墨烯二硫化钼生长与机理方面:通过气固输运方法和化学气相沉积(CVD)方法成功制备出单层二硫化钼;发现了二硫化钼二维层状材料生长过程中局域范德华作用力自发诱导的非对称应变。研究发现气固输运法生长温度较高且窗口较窄,反应过程对氧气较为敏感,二硫化钼二维原子晶体尺寸100μm以下;CVD方法对衬底依赖性小,可生长出尺寸大于100μm的单晶样品。此外,两种方法所制备的二维层状材料都具有均匀的厚度、元素分布,较高的晶体质量,优异的光致荧光。观察到二硫化钼二维层状材料中局域化范德瓦尔堆叠结构,通过拉曼光谱以及第一性原理模拟结果证明了局域化范德瓦尔堆叠的方式会在样品中产生轴向应力,并且估算出这个应力大约在0.5%左右,PL峰位的移动证明了这种局域化范德瓦尔相互作用会对此材料的光学带隙有明显的调控作用。这表明在这种超薄二硫化钼材料中即使没有外加应力而通过有限的晶体边界以及层间相互作用会对层间结构有显著的影响。基于二维层状材料模块化层层堆积的可控制性,这种局域化的范德瓦尔斯堆叠同样提供了一种调控材料本征物理性能的方法,而避免了外加应力的繁琐和不便。(2)类石墨烯二硫化钼材料的复合:通过CVD方法制备单层MoS2(1-x)Se2x,Mo(1-x)WxS2复合材料,并用液相方法把一维纳米结构生长在二维单层结构上,实现了对二硫化钼材料的结构与特性的调控。本论文讨论了两种基于二硫化钼的复合材料,第一种是采用CVD方法通过渡金属硫化物相互掺杂的方式制备的合金化的单层MoS2(1-x)Se2x,Mo(1-x)WxS2材料,通过控制掺杂原料的比例可以精细的调控掺杂浓度,同时证明了用Raman光谱的手段可以准确地判断出掺杂元素的种类以及估算出掺杂浓度。经过PL测试分析,我们证明了通过这种方式可以将掺Se、W的合金化单层材料的带隙从1.55 eV(MoSe2)到1.97 eV(WS2)精细调控,从而满足不同功能的需求。由于PL峰位对掺杂浓度非常敏感,因此可以通过测量合金化后PL峰位的偏移幅度反向推算掺杂浓度。第二种是采用CVD和水热法结合的方式制备出二硫化钼/氧化锌纳米棒复合结构,证明了单层二硫化钼不仅可以较好的作为氧化锌纳米棒生长的种子层,不会导致相互的晶格畸变,而且可以保证氧化锌纳米棒垂直生长的趋向性,而氧化锌在这种复合结构中起到“天线”的光聚焦效果,使得底部二硫化钼的光学信号被增强。这种复合结构中两种材料性能互相融合,相得益彰,是二维纳米材料和一维材料相互复合提升性能的典型例子。(3)基于单层二硫化钼超薄范德瓦尔斯异质结研究方面:设计并验证了MoTe2/MoS2二维单层II类异质结中的层间红外跃迁,并获得了二维异质结红外探测原型器件。利用自搭建的转移平台首次制备了单层MoTe2/MoS2异质结样品,理论计算和KPFM结果表明其能带组合方式为II类构型,与一些文献的预判符合一致,我们用Raman光谱、PL光谱观测到了MoTe2/MoS2之间强烈的层间耦合相互作用。利用KPFM测试手段首次在单层MoTe2/MoS2异质结中观测到光生载流子的产生和分离,证实了我们制备的这种超薄范德瓦尔斯异质能够实现电学功能。利用单层MoTe2/MoS2异质结制备了光响应测试的原型器件,测试结果表明MoTe2/MoS2异质结突破了纯单层MoTe2和MoS2的光响应截止波段,利用II类带间激发对1550 nm波段同样能够实现光响应。这预示了II类原子层的范德瓦尔斯异质结同样可以实现层间激发,在光探测方面有进一步研究的价值。
[Abstract]:Over the past ten years, graphene has excellent mechanical, optical and electrical properties has attracted great attention, and the potential application in the field of Optoelectronics and microelectronics is huge. In recent years, transition metal chalcogenides two-dimensional atomic crystals materials exhibit physical properties of graphene do not have many, extensive research shows that the a transistor, a light detector, has great application prospect of photovoltaic cell and so on. This paper can control for transition metal chalcogenide materials by two-dimensional atomic crystals and Van Der Waals heterojunction, focusing on two molybdenum sulfide two-dimensional atomic crystal material vapor growth and composite, and the properties and application of two-dimensional Van Der Waals heterojunction single-layer atom based on crystal. Made progress in the following aspects: (1) graphene like MoS2 and growth mechanism: Pass Gas solid transport method and chemical vapor deposition (CVD) method was successfully prepared by single MoS2; found asymmetric strain MoS2 two-dimensional layered material growth process induced by spontaneous local Fan Dehua force. The study found that the gas-solid transport growth method and high temperature window is narrow, the reaction process is sensitive to oxygen, molybdenum disulfide two-dimensional atomic crystal size of less than 100 mu m; CVD method of substrate dependent crystal growth can be small, the sample size of more than 100 mu m. In addition, two methods for two-dimensional layered composites with uniform thickness, element distribution, high crystal quality, excellent light induced fluorescence. Van Derwal stack structure the localization of two-dimensional layered materials in MoS2 were observed by Raman spectroscopy and first principle simulation results show the localization of Van de Waal stacking manner will produce axial in the sample Stress, and the stress is estimated at about 0.5% PL peak move proved the localization van Derwal interactions of this material in the optical band gap had obvious effects. This shows that in the thin material MoS2 even without external stress and through the crystal boundary and inter layer Co. the role of the interlayer structure will have a significant impact. A two-dimensional layered modular material accumulation can be controlled based on the localization of the Van Der Waals stack also provides a control method of the intrinsic physical properties of materials, and avoid the external stress the cumbersome and inconvenient. (2) composite materials of graphene like MoS2 MoS2: single by CVD method (1-x Se2x), Mo (1-x) WxS2 composites by liquid phase method, and the one dimensional nanostructures in two-dimensional single-layer structure, the realization of two molybdenum sulfide materials The regulation of structure and characteristics. This paper discusses two types of composite materials based on MoS2, the first is the use of the CVD method by transition metal sulfide mutual doping was prepared by way of alloying layer MoS2 (1-x) Se2x, Mo (1-x) WxS2 material, by controlling the doping ratio of raw materials can be precise control of doping concentration at the same time, we have proved that the Raman spectral method can accurately judge the type of doping elements and doping concentration is estimated. After PL test, we proved that this way can be mixed with Se, the band gap of W alloy single-layer materials from 1.55 eV (MoSe2) to 1.97 eV (WS2) regulation. In order to meet the different requirement. Because the PL peak is very sensitive to the doping concentration, so it can be measured by alloying PL peak amplitude offset reverse calculation of doping concentration. Second is the combination of CVD and hydrothermal method Preparation of molybdenum disulfide / Zinc Oxide nanorod composite structure, that not only can be used as a single-layer Zinc Oxide nanorod growth seed layer, will not lead to lattice distortion of each other, but also can guarantee the trend of Zinc Oxide and Zinc Oxide in the vertical growth of nanorods, in this composite structure to the light focusing effect of antenna, the optical signal at the bottom of MoS2 was increased. Two kinds of material properties of the composite structure of mutual integration, complement each other, is a typical example of two dimensional nano materials and composite materials are one-dimensional improved performance. (3) single-layer slim Van Der Waals heterojunction research: Based on the design and verification of MoTe2/MoS2 II heterojunction two-dimensional monolayer between layers in the infrared the transition, and obtained a 2D heterojunction infrared detection prototype device. Using the self transfer platform was prepared for the first time MoTe2/MoS2 single heterojunction sample, theoretical calculation and KPFM results show that the band combination for the II class configuration, and some literature to predict the consistency, we use the Raman spectra, PL spectra were observed between MoTe2/MoS2 strong interlayer coupling interaction. By using the KPFM test method for the first time in the single MoTe2/MoS2 heterostructure observation to produce and the separation of photogenerated carriers, we confirmed this slim Van Der Waals prepared to achieve heterogeneous electrical function. The light response test prototype devices were prepared by a single MoTe2/MoS2 heterojunction system, the test results show that the MoTe2/MoS2 heterojunction breaking the pure monolayer MoTe2 and MoS2 photoresponse cut-off band, using II band the excitation wavelength of 1550 nm to achieve the same light response. This indicates that the Van Der Waals class II heterojunction atomic layer can be achieved between layers of excitation in optical detection in The value of one step of research.

【学位授予单位】：中国科学院研究生院(上海技术物理研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ136.12

【引证文献】