二维传感器材料的合成及化学成分空间结构分布调制

发布时间：2018-07-20 21:38

【摘要】：由于零的带隙,石墨烯在电子和光电子领域的应用受到了极大限制。以单层Mo S_2为代表的二维过渡金属二硫族化合物(2D-TMDs)有非零带隙,这引起了人们的极大兴趣。以2D-TMDs为代表的二维半导体材料由于其拥有超薄、柔性、半导体性(合适的带隙)、丰富的激子动力学、谷极化、极高的比表面、低成本等一系列性质在新一代传感器领域有着重要的应用前景。为了充分开发这些二维半导体材料在电子和光电子领域以及基于二维电子、光电子的新型传感器领域的应用潜力,需要精确调制这些二维原子晶体的化学成分、结构、和电子性质及其成分的空间分布,本文要内容包括如下几点:(1)我们首先合成了基本的2D-TMDs,在此基础上,采用横向异质外延和原位改变反应物的策略,在国际上率先生长了二维半导体横向异质结,得到了二维WS_2-WSe_2、Mo S_2-Mo Se_2横向异质结。异质结在光学显微镜和在原子力显微下(AFM)呈现规则的三角形等形状,厚度均匀,表面光滑,样品为单层、双层或少层。拉曼和荧光研究表明实现了不同二维半导体在空间分布上的调制,不同的二维半导体(如WS_2和WSe_2)在光学分辨极限下没有明显的重叠和空隙,异质结中不同的二维半导体是无缝连接的。透射电镜和电子衍射研究表明了异质的单晶结构。用X射线能谱仪进行的元素分布研究表明实现了对异质结成分的空间分布的调制。用原子级薄的WSe_2-WS_2异质结制备了电子、光电子器件,包括二极管和三极管,器件显示出优秀整流行为和光电流产生行为。我们还指出了二维半导体横向异质结在传感器的可能应用。在制备的横向异质结的基础上,提出了二维异质结中“界面”向“界线”变的概念。(2)为了充分开发2D-TMDs等二维半导体在传感器领域的应用潜力,精确控制这些二维半导体的带隙和电子性质是很必要的。我们首先合成了二维WS_(2x)Se_(2-2x)半导体合金纳米片,控制了合金的成分。微拉曼研究表明了拉曼共振频率随着成份变化的连续变化。微荧光研究显示了荧光峰的位置随着成份连续变化,实现了对合金纳米片的能带带隙的调控。透射电镜研究证实了合金纳米片是均匀的单晶结构,结晶质量良好,合金纳米片的晶格参数随着成份连续变化。电性能的研究表明二维WS_(2x)Se_(2-2x)半导体合金纳米片的电子学性质,包括载流子类型和浓度、阀电压、载流子迁移率随着合金化学成份连续变化。本研究是设计具有可控响应和器件特性的二维电子、光电子器件以及建立在二维电子、光电子基础之上的传感器过程中的关键一步。(3)我们对2D-WS_2进行了高温P蒸汽处理,实现了对2D-WS_2的电子学性能的控制。光学显微镜表明P掺杂不改变纳米片的外观,AFM显示我们的样品是单层和少层样品。微拉曼研究表明了P掺杂基本不明显改变样品的声子结构。微荧光研究表明P掺杂一定程度改变了纳米片的电子结构。电性能的研究表明P掺杂改变了纳米片的半导体特性,掺杂后的2D-WS_2可控地呈现为n型、双极性和P型半导体特性。研究成果为建立在二维半导体基础之上的小型化、柔性化、集成化、智能化、网络化传感器的设计制备奠定了基础。本论文的研究成功地控制了二维半导体的成份、结构、电子性质及其空间分布,提供了一个重要的实现原子级薄的二维电子、光电子和传感器的材料平台,为新一代的集成电路和高柔性高灵敏的传感器等的设计提供了坚实的基础。
[Abstract]:Because of the zero band gap, the application of graphene has been greatly restricted in the field of electron and photoelectron. The two-dimensional transition metal two sulfur compound (2D-TMDs), represented by single layer Mo S_2, has non zero band gap, which has aroused great interest. The two-dimensional semiconductor material represented by 2D-TMDs has the ultra thin, flexible and semiconductor properties. The rich exciton dynamics, valley polarization, high specific surface and low cost have important applications in the field of new generation of sensors. In order to fully develop the potential applications of these two dimensional semiconductor materials in the field of electronic and photoelectrons and the new sensor field based on two dimensional electrons and photoelectrons. The composition, structure, and electronic properties and the spatial distribution of these two dimensional atomic crystals are precisely modulated. The contents of this article include the following points: (1) we first synthesized the basic 2D-TMDs, based on the strategy of using the transverse heteroepitaxy and in situ change of reactant, and the two dimensional semiconductor crosswise was grown at the international rate. Heterojunction, the two-dimensional WS_2-WSe_2, Mo S_2-Mo Se_2 transverse heterojunction was obtained. The heterojunction in the optical microscope and the atomic force microscopy (AFM) presented the regular triangular shape. The thickness is uniform and the surface is smooth. The sample is a single layer, double layer or less layer. Raman and fluorescence studies show the modulation of different two-dimensional semiconductors on the spatial distribution. Different two-dimensional semiconductors (such as WS_2 and WSe_2) have no obvious overlap and gap at the optical resolution limit. Different two-dimensional semiconductors in the heterojunction are seamlessly connected. Transmission electron microscopy and electron diffraction studies show heterogeneous single crystal structures. The study of the distribution of elements in the X ray spectrometer shows that the composition of the heterojunction is realized. Modulation of spatial distribution. Electronic, optoelectronic devices, including diodes and triode, are prepared by atomic thin WSe_2-WS_2 heterojunction. The devices show excellent rectifying behavior and photocurrent generation behavior. We also point out the possible use of two dimensional semiconductor transverse heterojunction in the sensor. On the basis of the prepared transverse heterojunction, it is proposed. The concept of "interface" to "boundary" changes in two-dimensional heterojunction. (2) in order to fully develop the potential application of 2D-TMDs and other two-dimensional semiconductors in the field of sensors, it is necessary to accurately control the band gap and electronic properties of these two-dimensional semiconductors. We first synthesized two dimensional WS_ (2x) Se_ (2-2x) semiconductor alloy nanoscale and controlled the alloy. The micro Raman study shows that the frequency of the Raman resonance varies continuously with the variation of the composition. The micro fluorescence study shows that the position of the fluorescence peak is controlled by the continuous variation of the composition, and the band gap of the alloy nanoscale is regulated. The transmission electron microscope studies confirm that the alloy nanoscale is homogeneous single crystal structure with good crystalline quality. The electronic properties of the two-dimensional WS_ (2x) Se_ (2-2x) semiconductor nanoscale, including the carrier type and concentration, the valve voltage, and the carrier mobility with the chemical composition of the alloy continuously change. This research is designed to design two-dimensional electricity with controllable response and device characteristics. Sub, optoelectronic devices and a key step in the sensor process based on two-dimensional electron and photoelectrons. (3) we carried out high temperature P steam treatment to 2D-WS_2 to achieve the control of the electronic performance of 2D-WS_2. The optical microscope shows that P doping does not change the appearance of nanoscale, and AFM shows that our samples are single layer and less layer. The micro Raman study shows that P doping does not change the phonon structure of the sample basically. The micro fluorescence study shows that the doping of P has changed the electronic structure of the nanoscale. The study of electrical properties shows that the doping of P has changed the semiconductor properties of the nanoscale, and the doped 2D-WS_2 is n, bipolar and P type semiconductor. The research results laid the foundation for the small, flexible, integrated, intelligent, and networked sensors based on the two-dimensional semiconductor, which successfully controlled the composition, structure, electronic properties and spatial distribution of two dimensional semiconductors, and provided an important two-dimensional electron to achieve atomic thin. The material platform of Optoelectronics and sensors provides a solid foundation for the design of the new generation of integrated circuits and highly flexible and highly sensitive sensors.
【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TP212;TN304

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