硅烯场效应晶体管中电子自旋和谷自由度的全电学调控

发布时间：2019-04-26 18:09

【摘要】：自石墨烯成功制备以来,许多新型二维材料备受物理学和材料科学领域研究者的关注,比如六角氮化硼、二硫化钼以及黑磷等。作为类石墨烯结构的硅烯具有翘曲结构,由于其电子融合了谷、自旋等多重自由度,是近年来前沿领域重点关心的对象之一,已在2012年由Vogt等人制备出来。对硅烯材料电子性质的研究进一步推动了当代电子学概念、理论及应用前景的发展。基于硅烯实验和理论上的最新研究进展,本论文基于硅烯新奇的物理性质设计了场效应管装置,从理论上提出自旋和谷自由度的全电学控制的方法。具体内容安排如下:第一章主要介绍二维材料的兴起、制备以及应用前景,硅烯材料的结构及基本的电子性质和基于二维材料场效应管的实验与理论方面的研究进展。第二章简单介绍研究硅烯场效应管电子输运性质常用的理论方法,包括有效质量模型-Dirac方程理论、紧束缚近似方法、Landauer-Buttiker理论、格林函数方法以及密度泛函理论。第三章主要阐述如何利用反铁磁场来实现硅烯自旋和谷自由度的独立控制。利用有效质量-Dirac方程和Landauer-Buttiker理论可以证明,在由一个npn结构建的硅烯场效应管中可以实现支持单谷和单自旋输运的谷选择性自旋滤波器(VSSF)。这一场效应管的p型掺杂区外加反铁磁交换场和垂直电场,VSSF特性的实现得益于自旋极化的单谷狄拉克锥可电控状态。这些结果与先前的一些理论计算结果及第一性计算的能带结果都是一致的。第四章详细介绍实现硅烯自旋-谷自由度的全电学控制的新方案。通过理论推导和数值计算,我们探讨了铁磁硅烯器件中的自旋谷极化输运,其中铁磁硅烯器件局部是被层间电场(zE)控制,通过调节zE电场可以实现具有100%的谷选择的自旋极化输运的谷自旋过滤器。我们的结果为未来逻辑电路中同时控制谷和自旋两种自由度提供了一条有效途径。第五章给出总结和展望。
[Abstract]:Since the preparation of graphene, many new two-dimensional materials, such as hexagonal boron nitride, molybdenum disulfide and black phosphorus, have attracted much attention in the field of physics and material science. As a graphene-like structure, silene has warped structure, because of its electron fusion valley, spin and other multiple degrees of freedom, it is one of the most important objects in the frontier field in recent years. It was prepared by Vogt et al in 2012. The research on the electronic properties of silicene materials has further promoted the development of the concept, theory and application of modern electronics. Based on the latest research progress of silicene experiment and theory, a novel field effect transistor (FET) device is designed based on the novel physical properties of silene, and the method of all-electric control of spin and valley degrees of freedom is proposed theoretically. The main contents are as follows: in the first chapter, the rise, preparation and application prospect of two-dimensional materials, the structure and basic electronic properties of silene materials, and the research progress of experiment and theory based on two-dimensional material field effect tubes are introduced. The second chapter briefly introduces the theoretical methods commonly used to study the electron transport properties of silene FET, including effective mass model-Dirac equation theory, tight binding approximation method, Landauer-Buttiker theory, Green's function method and density functional theory. The third chapter mainly describes how to use antiferromagnetic field to realize the independent control of spin and valley degrees of freedom of silene. By using the effective mass Dirac equation and Landauer-Buttiker theory, it is proved that a valley selective spin filter (VSSF). Supporting single valley and single spin transport can be realized in a silene FET constructed by a npn structure. An antiferromagnetic exchange field and a vertical electric field are applied to the p-type doped region of the FET. The realization of the VSSF characteristics is due to the electronically controlled state of the spin-polarized single-valley Dirac cone. These results are consistent with some previous theoretical results and the energy band results of first-nature calculations. In chapter 4, a new scheme to realize all-electric control of spin-valley degree of freedom of silicene is introduced in detail. Through theoretical derivation and numerical calculation, we discuss spin valley polarization transport in ferromagnetic silicon devices, in which ferromagnetic silicon devices are partially controlled by interlaminar electric field (zE), and the spin valley polarization transport in ferromagnetic silicon devices is controlled locally by the interlayer electric field. A valley spin filter with 100% valley selective spin polarization transport can be realized by adjusting the zE electric field. Our results provide an effective way to control both the valley and spin degrees of freedom in future logic circuits. The fifth chapter gives the summary and prospect.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN386

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