【作者】 程帅；

【导师】 常海欣；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2017， 硕士

【摘要】 自2004年石墨烯被偶然发现以来,新型的二维材料以其独特和优异的物理化学性质引起了极大的关注,在电学器件、光电子器件、能源存储、复合材料、催化、传感器等领域都有广泛的应用前景。除了石墨烯以外,过渡金属硫化物（TMDCs）是近些年来最受关注的一类新型二维材料。尽管对块状TMDCs的研究已经有几十年的历史,随着近年来对二维材料的制备方法和表征手段的研究不断深入,单层或少层的二维TMDCs越来越引起了科研工作者的兴趣。在过渡金属硫化物大家族中,关于二碲化钼（MoTe₂）的研究还处于起步阶段,可控制备高质量的MoTe₂是研究其性质与应用的基础,由于MoTe₂自身的特性同时也是重点与难点。本文研究了使用化学气相沉积来制备MoTe₂薄膜的方法,通过控制生长过程中的实验条件实现了对MoTe₂晶相的控制,可以在一个硅片上同时生长两种晶相的大面积MoTe₂,也可以有选择地在整个硅片上生长1T’相或者2H相MoTe₂薄膜。主要内容如下:1、使用单温区管式炉在硅片上生长出了大面积的MoTe₂薄膜。2、生长过程中位于碲粉正上方总会生成1T’相MoTe₂,而在陶瓷舟外侧的MoTe₂则与降温速率有关,在慢速降温时会生成大面积2H相MoTe₂,在快速降温时生长的是1T’-2H相MoTe₂同质结。通过一系列的表征说明生长出的MoTe₂薄膜均匀度和结晶性良好,晶相界面处没有明显的过渡层。3、碲源和衬底之间的距离、碲粉的用量会影响碲蒸气的浓度,从而决定生长的MoTe₂薄膜的晶相。通过将衬底正面朝下放置于碲源上游和下游的位置,成功地在整个硅片上生长出了单一晶相的MoTe₂薄膜。更多还原

【Abstract】 Since graphene was synthesized by accident in 2004,two dimensional materials have been attracting increasing interest because of their unique structure and prominent properties,which make them promising materials for a wide range of applications related to,e.g.,electronics,optoelectronics,energy storage,composite material,catalysis and sensor.Except for graphene,transition metal dichalcogenides（TMDCs）is one of the most remarkable two-dimensional materials in recent years.Although the study of bulk TMDCs has decades of history,monolayer or few-layered 2D TMDCs gains the popularities of researchers with the development of synthesis method and characterization tools for two dimensional material.Among TMDCs family,the study of MoTe₂ is still in start stage,the research of its properties and application is based on the controlled synthesis of high quality MoTe₂,which is important and difficult at the same time.In this paper,we synthesize MoTe₂ films by chemical vapor deposition,and we realize the phase control of MoTe₂ by adjusting the experiment conditions in the growth process.Two phases of large area MoTe₂ films can be synthesized on one silicon wafer,and single phase（1T’or 2H）MoTe₂ can also be grown on the whole area of silicon wafer.The main contents are as follows:1.We use single temperature zone tube furnace to synthesize large area MoTe₂ films on silicon wafer.2.1T’phase MoTe₂ films are always produced right above the Te powder,however,the phase of MoTe₂ located on the edge of silicon wafer depends on the cooling rate when the experiment is finished.That is,large area 2H phase MoTe₂ films can be synthesized in slow cooling rate,while 1T’-2H phase MoTe₂ homojunctions can be synthesized in fast cooling rate.A series of characterizations suggest that the synthesized MoTe₂ films is homogeneous and high-crystallinity,and there is no obvious transition region between two phases.3.The amount of tellurium and the distance between substrate and tellurium source make a difference in the concentration of Te vapor,as well as the phase of the MoTe₂ film.What’s more,MoTe₂ films of large area and single phase can be grown successfully on the substrate that is facing down and located about 3cm away upstream or downstream from Te powder.更多还原