掺杂单晶硅纳米结构力热耦合模型的研究

发布时间：2018-01-08 23:01

本文关键词：掺杂单晶硅纳米结构力热耦合模型的研究　出处：《新疆大学》2017年硕士论文　论文类型：学位论文

【摘要】：纳机电系统相比于微机电系统,在尺寸上具有很大的优势,它在特征尺寸以及效应上具有纳米技术的特点,在现代技术中具有广泛的应用前景。在纳机电系统材料中,应用最广的材料是硅纳米材料,尺寸对硅纳米材料的性能具有很大的影响,由于硅纳米材料尺寸的变化,由微米尺寸转变到了纳米尺寸,使得单晶硅材料的性能,例如力学、热学、电学、光学以及磁学等方面的性能发生了很大的变化,因此硅纳米材料性能的研究也变的尤为重要。掺杂对于硅纳米材料具有重要的意义,掺杂提高了硅纳米材料的物理性能,进而提高了它的应用价值。本文分别通过理论计算方法和分子动力学方法研究了替代掺杂单晶硅纳米结构的力热耦合特性。论文主要分为以下三个部分:(1)基于半连续体模型的理论计算方法,建立了掺杂硅纳米结构的解析模型并考虑了温度效应,研究了P掺杂硅纳米薄膜的杨氏模量与硅纳米梁的谐振频率。结果表明,掺杂硅纳米薄膜的杨氏模量随着温度的升高呈现减小的趋势;硅纳米梁的谐振频率也随温度的升高而减小,但是谐振频率随着温度升高而减小的趋势并不明显,即温度并不是影响硅纳米梁谐振频率的主要因素。(2)通过分子动力学方法模拟研究了P元素与B元素掺杂硅纳米梁的谐振频率,模拟分析了长度方向尺寸、掺杂浓度以及厚度方向与宽度方向尺寸的乘积对硅纳米梁谐振频率的影响。结果表明,长度方向、厚度方向和宽度方向尺寸对硅纳米梁谐振频率的影响较大,谐振频率随长度方向尺寸的增大而减小,随着厚度方向与宽度方向尺寸乘积的增大而增大;谐振频率随着掺杂浓度的增大而增大,但增大的趋势不明显,即影响硅纳米梁谐振频率的主要因素是尺寸。(3)通过分子动力学方法模拟研究了温度对P与B掺杂硅纳米梁谐振频率的影响。结果表明,谐振频率随着温度的升高而减小,但是趋势并不明显。并将模拟结果与计算结果进行了对比,两种方法得到的结果趋势是一致的。本论文通过理论计算与模拟两个方面研究了掺杂硅纳米结构的力热耦合特性,得出了一些成果,对掺杂硅纳米结构其它性能的研究具有一定的参考价值。
[Abstract]:Compared with micro electromechanical system, nano electromechanical system has great advantages in size, and it has the characteristics of nanotechnology in characteristic size and effect. The most widely used materials in nanoelectromechanical systems are silicon nanomaterials, the size of which has a great influence on the properties of silicon nanomaterials. Due to the change of the size of silicon nanomaterials from micron size to nanometer size the properties of monocrystalline silicon materials such as mechanical thermal electrical optical and magnetic properties have been greatly changed. Therefore, it is very important to study the properties of silicon nanomaterials. Doping is of great significance to silicon nanomaterials, and doping improves the physical properties of silicon nanomaterials. In this paper, the mechanical and thermal coupling characteristics of the substituted monocrystalline silicon nanostructures are studied by theoretical calculation and molecular dynamics methods. The thesis is divided into three parts: 1). The theoretical calculation method based on semi-continuum model. The analytical model of doped silicon nanostructures was established and the temperature effect was taken into account. The Young's modulus and resonant frequency of silicon nanocrystals were studied. The Young's modulus of doped silicon nanocrystalline films decreases with the increase of temperature. The resonant frequency of silicon nanocrystalline beam also decreases with the increase of temperature, but the decreasing trend of resonant frequency is not obvious with the increase of temperature. That is, temperature is not the main factor affecting the resonant frequency of silicon nanocrystalline beam. (2) the resonant frequency of P element and B element doped silicon nanobeam is simulated by molecular dynamics method, and the dimension of length direction is simulated and analyzed. The effect of doping concentration and the product of thickness direction and width direction on the resonant frequency of silicon nanocrystalline beam is studied. The results show that the length direction, thickness direction and width direction have great influence on the resonant frequency of silicon nanocrystalline beam. The resonant frequency decreases with the increase of the length dimension and increases with the increase of the dimension product of the thickness direction and the width direction. The resonant frequency increases with the increase of doping concentration, but the increasing trend is not obvious. The influence of temperature on resonant frequency of P and B doped silicon nanocrystalline beams is studied by molecular dynamics method. The results show that the effect of temperature on the resonant frequency of silicon nanocrystalline beams is studied by means of molecular dynamics. The resonant frequency decreases with the increase of temperature, but the trend is not obvious. The results obtained by the two methods are consistent. In this paper, the mechanical and thermal coupling characteristics of doped silicon nanostructures are studied by theoretical calculation and simulation, and some results are obtained. The study of other properties of doped silicon nanostructures has certain reference value.
【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O613.72;TB383.1

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