二维黑磷材料红外太赫兹光电性质研究

发布时间：2018-03-11 11:08

本文选题：二维材料　切入点：黑磷　出处：《东华大学》2017年硕士论文　论文类型：学位论文

【摘要】：自从二维材料被发现以来,因为其在电子器件以及光子器件的应用方面存在极大的潜能,引起了人们的广泛研究。二维材料具有独特的物理性质,如二维电子气的超导现象与各向异性的传输特性等等,并且在他们的多层结构中也有这种现象。本文简单阐述了一些二维材料的电学性质与光学性质的研究现状,并且在之后结合泊松方程与电子/空穴连续方程,以及漂移扩散方程,讨论了二维材料黑磷场效应晶体管的双极性电学特性,最后用时域有限差分法讨论了单层黑磷器件的太赫兹辐射吸收的性质。论文的主要内容如下:第一,本文首先考虑了块材的黑磷场效应晶体管,当肖特基势垒相对于电子和空穴相同时,随沟道长度的变化,黑磷场效应晶体管的双极性特性的变化规律。得到了黑磷的场效应晶体管双极性特性随沟道长度变短而变得更加明显的结论。之后通过分析对比具有100nm沟道长度以及2μm沟道长度的晶体管的能带图,得到了黑磷场效应晶体管的双极性转换机制与沟道长度有关并且受肖特基势垒高度影响的结论。第二,接下来讨论了黑磷的层数厚度以及肖特基势垒高度对黑磷场效应晶体管的双极性的影响。当肖特基势垒相对于电子与空穴相同时,不同层数黑磷的场效应晶体管双极性特性都随沟道长度变短而变得更加明显。与此同时输出饱和电流随黑磷的层数厚度增加而增加。之后研究分析了黑磷场效应晶体管的电势分布与电子浓度分布。并由此讨论了肖特基势垒高度,黑磷层数厚度,以及器件沟道长度如何影响输出特性,包括载流子注入与双极性特性。第三,研究了当改变肖特基势垒高度时,不同层数厚度与不同沟道长度的黑磷场效应晶体管的双极性变化规律。得到当不同层数的晶体管的肖特基势垒高度相对空穴均为0.24e V时,单层的黑磷晶体管呈单极性特性,并且随黑磷层数的增加,电流开关比可以从1010变化到103。第四,研究了一种具有纳米带结构的单层黑磷器件,并通过数值计算证明,在纳米结构的单层的黑磷中可以激发局域表面等离子体。并讨论了纳米带结构的单层黑磷在太赫兹范围内的光学吸收谱与透射谱。然后研究了黑磷纳米带宽度对共振频率与吸收率的关系。发现随着黑磷纳米带的宽度变大当器件的太赫兹辐射的吸收峰值产生的频率即共振频率逐渐变小。最后讨论了入射光的偏振对等离子振荡的影响。得到了单层黑磷纳米带器件的共振频率位置基本不随入射光的偏振方向而改变,但是吸收率的峰值随入射光的偏振方向有较明显的变化,随着偏振角度的增大吸收率逐渐减小。
[Abstract]:Since the discovery of two-dimensional materials, due to their great potential in the applications of electronic devices and photonic devices, they have attracted extensive research. For example, the superconducting phenomena and anisotropic propagation characteristics of two-dimensional electron gas, and so on, are also found in their multilayer structures. In this paper, the present situation of the study on the electrical and optical properties of some two-dimensional materials is briefly described. After that, the bipolar electrical properties of the two dimensional black phosphorus field effect transistors are discussed by means of Poisson equation, electron / hole continuum equation and drift diffusion equation. Finally, the properties of terahertz radiation absorption of monolayer black phosphorus devices are discussed by using the finite-difference time-domain method. The main contents of this paper are as follows: firstly, the black phosphorus field effect transistors are considered in this paper. When the Schottky barrier is the same as the electron and hole, it varies with the channel length. It is concluded that the bipolar characteristics of black phosphorus field-effect transistors become more obvious as the channel length becomes shorter. Then, by analyzing and comparing the bipolar characteristics of black phosphorus field-effect transistors with 100nm channel length, we obtain the conclusion that the bipolar characteristics of black phosphorus field-effect transistors become more obvious with shorter channel length. And the energy band diagram of the 2 渭 m channel length transistor, It is concluded that the bipolarity conversion mechanism of black phosphorus field effect transistors is related to channel length and affected by Schottky barrier height. The influence of the thickness of the black phosphorus layer and the Schottky barrier height on the bipolarity of the black phosphorus field effect transistor is discussed. When the Schottky barrier is the same as the electron hole, The bipolar characteristics of different layers of black phosphorus transistors become more obvious with the channel length becoming shorter. At the same time, the output saturation current increases with the increase of the layer thickness of black phosphorus. The field effect of black phosphorus is studied and analyzed. The potential distribution and electron concentration distribution of transistors are discussed, and the Schottky barrier height is discussed. The thickness of the black phosphorus layer and the channel length of the device affect the output characteristics, including carrier injection and bipolar characteristics. Thirdly, when the Schottky barrier height is changed, The bipolarity of black phosphorus field-effect transistors with different layer thickness and channel length is obtained. When the Schottky barrier height of different layers is 0.24e V, the single-layer black phosphorus transistors are unipolar. With the increase of the number of black phosphorus layers, the current-switching ratio can be changed from 1010 to 103. 4th. A kind of monolayer black phosphorus device with nanobandle structure is studied, and the numerical results show that the current switching ratio can be changed from 1010 to 103. 4th. Local surface plasmas can be excited in black phosphorus monolayer of nanostructures. The optical absorption and transmission spectra of black phosphorus monolayers with nanobelts in terahertz range are discussed. The relationship between resonance frequency and absorptivity. It is found that as the width of black phosphorus nanobelts increases as the absorption peak of terahertz radiation of the device becomes smaller, the resonance frequency is gradually reduced. Finally, the polarization of incident light to plasma is discussed. It is obtained that the resonance frequency position of the monolayer black phosphorus nanostrip device basically does not change with the polarization direction of the incident light. However, the peak absorptivity varies obviously with the polarization direction of the incident light, and decreases with the increase of the polarization angle.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN386

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