AlGaN超晶格界面调控及其电学特性

发布时间：2018-02-13 21:39

本文关键词： III-V族半导体 GaN/AlN超晶格第一性原理带隙缺陷　出处：《北京工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：GaN、AlN以及Ga N/AlN的异质结构作为第三代半导体在紫外发光器件以及在高功率、高频、高温等电子器件等方面具有广泛的应用。其中GaN/AlN半导体超晶格作为一种人工材料,可以通过调节势垒层的厚度比、控制掺杂等方式控制材料性质,引起了人们的广泛关注。本文基于密度泛函的第一性原理计算,通过研究纤锌矿与闪锌矿结构的GaN/AlN超晶格体系在不同势垒层的厚度比和掺杂离子情况下,系统探究结构调控、结构缺陷以及掺杂对电学性质的影响,这将为新型超晶格器件设计与研发提供理论指导,主要研究结果如下:首先,主要讨论本征半导体超晶格结构的带隙变化。结果表明:在保持超晶格总层数不变的情况下,无论是对纤锌矿或是闪锌矿结构体系,随着势垒层的加厚其能带间隙均呈现先减小后增大的抛物线的趋势。当超晶格势垒势阱层的厚度相等时,其带隙达到最小值。其次,主要研究空位缺陷对超晶格能带结构的影响。结果表明:氮空位为GaN/AlN半导体超晶格的主要缺陷。对于纤锌矿结构,阳离子缺陷(比如Al或者Ga空位)易在界面B(GaN区域的最后一层Ga层和AlN区域的第一层Al层之间的界面),而阴离子缺陷(N空位)易在势阱层(GaN区域)内形成。最后,主要研究掺杂Mg和Si离子对纤锌矿和闪锌矿两种结构的能带结构的影响。研究发现,对于纤锌矿和闪锌矿体系,Si原子掺入结构的形成能比Mg原子的形成能低,表明Si掺杂原子较易引入结构,并且杂质易引入势阱(GaN)区。同时,发现闪锌矿结构较纤锌矿结构更易于掺杂。
[Abstract]:Gan / AlN and GaN/AlN heterostructures are widely used as third generation semiconductors in ultraviolet luminescent devices and electronic devices such as high power, high frequency, high temperature, etc. Among them, GaN/AlN semiconductor superlattices are used as artificial materials. The properties of materials can be controlled by adjusting the thickness ratio of barrier layer and controlling doping. The effects of structure regulation, structural defects and doping on electrical properties of wurtzite / sphalerite GaN/AlN superlattice system were investigated systematically under different barrier layer thickness ratios and doping ions. This will provide theoretical guidance for the design and development of new superlattice devices. The main results are as follows: firstly, the band gap changes of intrinsic semiconductor superlattice structures are discussed. For wurtzite and sphalerite structures, the band gap decreases first and then increases with the thickening of barrier layer. When the thickness of the barrier well layer is equal, the band gap reaches the minimum. The effect of vacancy defects on the band structure of superlattices is studied. The results show that nitrogen vacancies are the main defects of GaN/AlN semiconductor superlattices. Cationic defects (such as Al or Ga vacancies) are easily formed at the interface between the last layer of Ga and the first layer of Al in the AlN region, while the anionic defects are easily formed in the potential well layer (gan). The effect of doping mg and Si ions on the energy band structure of wurtzite and sphalerite is studied. It is found that the formation energy of Si doped structure in wurtzite and sphalerite system is lower than that of mg atom. The results show that Si doped atoms are easy to be introduced into the structure and impurities to the potential well / gan region. It is also found that the sphalerite structure is more easily doped than wurtzite structure.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.2

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