单元素窄禁带半导体纳米结构的第一性原理研究

发布时间：2018-03-21 22:19

本文选题：带隙　切入点：第一性原理计算　出处：《华东师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：过去几十年,半导体纳米结构的研究引起了广泛关注,量子限域效应使其具备不同于体材料的新颖物性,从而能满足功能应用的需要。虽然IVA族元素C、Si Ge等众多体系的纳米线、纳米片、纳米带等纳米结构已经有了一系列的研究,然而,其物性和器件性能目前仍然有诸多不足,寻找和研究新型半导体纳米结构仍然非常必要。因此,本文研究了两种单元素窄禁带半导体的纳米结构,第一个是二维层状结构的单层和多层As结构(砷烯),第二个是Te的纳米线和纳米带结构。首先,本文通过第一性原理计算研究了二维褶皱蜂窝层状结构的As能带结构随层数、面内应变的变化规律,发现层数和面内应变会导致间接带隙到直接带隙的转变,而这种转变是由于间接和直接带隙的带边态对量子限制效应与应变的响应不同所导致,间接带隙的价带带边态来自于平行于层平面的As-As键,而直接带隙的价带带边态来自于垂直层平面的As-As键。其次,本文还通过第一性原理计算对Te纳米结构的表面性质与光学性质进行了研究。通过对Te表面性质的研究,发现不同密勒指数面的表面能均比IVA族元素C Si Ge的表面能低,并且通过低密勒指数面组合构成的一维纳米线结构都具有明显的带隙且没有引入任何表面电子态。通过对Te光学性质研究,发现Te晶体吸收谱在0-3 eV范围内的吸收峰主要是由于最靠近禁带的两个能带之间的电子直接跃迁所导致的；Te纳米线与纳米带结构的吸收峰随着尺寸的减小而逐渐蓝移,带隙随着尺寸的减小而显著增大。
[Abstract]:In the past few decades, the study of semiconductor nanostructures has attracted wide attention. Quantum limiting effect makes it have novel physical properties different from bulk materials, which can meet the needs of functional applications. There have been a series of studies on nanostructures such as nanochips and nanobelts. However, their physical properties and device properties still have many shortcomings, so it is still necessary to find and study new semiconductor nanostructures. In this paper, two kinds of nanocrystalline structures of narrow band gap semiconductor with single element are studied. The first is the single layer and multilayer as structure of two-dimensional layered structure, the second is the nanowire and nanoband structure of Te. In this paper, the variation of as energy band structure with the number of layers and the in-plane strain of two-dimensional folded honeycomb layered structure is studied by first principle calculation. It is found that the number of layers and in-plane strain will lead to the transition from indirect band gap to direct band gap. This transition is due to the different responses of the indirect and direct band edge states to the quantum confinement effect and the strain. The valence band edge states of the indirect band gaps are derived from the As-As bonds parallel to the layer plane. The valence band edge states of the direct band gap are derived from the As-As bond in the vertical plane. Secondly, the surface and optical properties of Te nanostructures are studied by first principle calculation. It is found that the surface energy of different Miller exponent surfaces is lower than that of IVA group element C Si GE. Moreover, the structure of one dimensional nanowire formed by the combination of low Miller exponent surface has obvious band gap and no surface electronic state is introduced. The optical properties of Te are studied. It is found that the absorption peak of Te crystal in the range of 0-3 EV is mainly due to the direct electron transition between the two energy bands closest to the band gap, which results in the blue shift of the absorption peaks of the nanowires and nanobelts with the decrease of the size. The band gap increases with the decrease of size.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304;TB383.1

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