Li、N不同掺杂构型对ZnO光电特性影响的研究
发布时间：2019-04-12 09:17
【摘要】：Zn O是一种新型的直接带隙宽带半导体,室温禁带宽度约为3.37e V,同时在室温下具有较大的激子束缚能(60me V),可以实现室温紫外激光发射。其在气敏传感器件、表面声波器件、压电器件、高温微电子器件和透明导电薄膜和紫外蓝光发射等方面具有良好的发展前景。本论文采用基于密度泛函理论框架下的第一性原理平面波赝势方法,计算分析了不同杂质结构对Zn O的电子结构和光学性质的影响。主要内容如下:1、研究Li、N不同掺杂结构与浓度对Zn O光电特性的影响。利用第一性原理平面波超软赝势方法计算了掺杂前后Zn O体系的电子结构和光学性质变化特性,分析了掺杂对Zn O晶体结构电子结构和光学性质的影响。计算了本征Zn O和li、N不同掺杂结构对Zn O的晶格常数、能带结构、电子态密度、介电函数、吸收系数的影响。结果表明:随着Li、N原子的掺入,体系的晶格常数略微变大,键长变长,体系的体积增大,系统的形成能为负值,体系稳定。费米能级进入价带,产生了空穴载流子,使得体系呈P型。但是在四受主掺杂中,两个Li-N缺陷均平行C轴且相邻的情况下,掺杂体系却显现出N型半导体特性。在高浓度掺杂中结构k(Li-2N缺陷的相邻位置出现一个Li-N不平行C轴的缺陷),体系也呈现N型特性,且结构的形成能相当低。说明杂质原子之间的作用会降低体系的形成能,形成施主补偿。结构l(Li-2N和不相邻的Li-N平行C轴),m(包含两个不相邻的Li-2N)缺陷的形成能为正值,说明过高浓度的掺杂不可行。2、M2-2N模型的电子结构。本文构建了M2-2N模型(M为与N共掺杂的Na、K、Ca、Cu、Mg、Al等原子),并对其电子结构进行了研究。计算结果表明Li2-N2掺杂模型的形成能低且呈现N型。通过对比分析,发现Na、K等原子与N共掺杂后体系呈现N型特性,而当M为Ag、Ba、Mg原子时掺杂体系呈现P型特性。电荷差分态密度显示Li、Na、K与N共掺杂时,N与N原子之间会形成共价键。本文计算结果为掺杂Zn O光电材料的设计与应用提供了理论参考,对新型光电材料与器件研发有着积极的意义。
[Abstract]:Zn O is a new type of direct band gap broadband semiconductor with a band gap of about 3.37eV at room temperature and a large exciton binding energy (60me V),) at room temperature. It has a good prospect in gas sensing devices, surface acoustic devices, piezoelectric devices, high temperature microelectronic devices, transparent conductive thin films and UV blue light emission. In this paper, the influence of different impurity structures on the electronic structure and optical properties of Zn O is calculated and analyzed by using the first-principle plane wave pseudopotential method based on density functional theory (DFT). The main contents are as follows: 1. The effects of different doping structures and concentrations of Li,N on the photoelectric properties of Zn O are studied. The electronic structure and optical properties of Zn-O system before and after doping have been calculated by using the first-principle plane wave ultra-soft pseudopotential method, and the effects of doping on the electronic structure and optical properties of Zn-O crystal have been analyzed. The effects of intrinsic Zn O and li,N doping structures on the lattice constant, band structure, electron density of state, dielectric function and absorption coefficient of Zn O were calculated. The results show that with the addition of Li,N atoms, the lattice constant of the system increases slightly, the bond length becomes longer, the volume of the system increases, the formation energy of the system is negative, and the system is stable. The Fermi energy level enters the valence band, resulting in a hole carrier, which makes the system P-type. However, in the case of four-acceptor doping, two Li-N defects are parallel to the C-axis and adjacent to each other, but the doping system exhibits N-type semiconductor characteristics. In the high concentration doping, the structure k (a defect in the adjacent position of the Li-2N defect is not parallel to the C axis of Li-N), the system also presents the N-type characteristics, and the formation energy of the structure is quite low. It shows that the interaction between impurity atoms will reduce the formation energy of the system and form donor compensation. The formation energy of structural l (Li-2N and non-adjacent Li-N parallel C-axis), m (contains two non-adjacent Li-2N) defects is positive, which indicates that excessive high concentration doping is not feasible. 2, the electronic structure of M2 + 2N model. In this paper, the M _ (2) O _ (2) N model (M is an Na,K,Ca,Cu,Mg,Al atom codoped with N) has been constructed and its electronic structure has been studied. The calculated results show that the formation energy of the Li2-N2 doping model is low and it is N-type. Through comparative analysis, it is found that the co-doped system of Na,K and N presents N-type, while the doped system shows P-type when M is Ag,Ba,Mg atom. The charge difference density of states shows that the covalent bond between N and N atoms will be formed when Li,Na,K codoped with N. The calculation results in this paper provide a theoretical reference for the design and application of doped Zn O photoelectric materials, and have a positive significance for the research and development of new photoelectric materials and devices.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.2;O483
本文编号：2456896
[Abstract]:Zn O is a new type of direct band gap broadband semiconductor with a band gap of about 3.37eV at room temperature and a large exciton binding energy (60me V),) at room temperature. It has a good prospect in gas sensing devices, surface acoustic devices, piezoelectric devices, high temperature microelectronic devices, transparent conductive thin films and UV blue light emission. In this paper, the influence of different impurity structures on the electronic structure and optical properties of Zn O is calculated and analyzed by using the first-principle plane wave pseudopotential method based on density functional theory (DFT). The main contents are as follows: 1. The effects of different doping structures and concentrations of Li,N on the photoelectric properties of Zn O are studied. The electronic structure and optical properties of Zn-O system before and after doping have been calculated by using the first-principle plane wave ultra-soft pseudopotential method, and the effects of doping on the electronic structure and optical properties of Zn-O crystal have been analyzed. The effects of intrinsic Zn O and li,N doping structures on the lattice constant, band structure, electron density of state, dielectric function and absorption coefficient of Zn O were calculated. The results show that with the addition of Li,N atoms, the lattice constant of the system increases slightly, the bond length becomes longer, the volume of the system increases, the formation energy of the system is negative, and the system is stable. The Fermi energy level enters the valence band, resulting in a hole carrier, which makes the system P-type. However, in the case of four-acceptor doping, two Li-N defects are parallel to the C-axis and adjacent to each other, but the doping system exhibits N-type semiconductor characteristics. In the high concentration doping, the structure k (a defect in the adjacent position of the Li-2N defect is not parallel to the C axis of Li-N), the system also presents the N-type characteristics, and the formation energy of the structure is quite low. It shows that the interaction between impurity atoms will reduce the formation energy of the system and form donor compensation. The formation energy of structural l (Li-2N and non-adjacent Li-N parallel C-axis), m (contains two non-adjacent Li-2N) defects is positive, which indicates that excessive high concentration doping is not feasible. 2, the electronic structure of M2 + 2N model. In this paper, the M _ (2) O _ (2) N model (M is an Na,K,Ca,Cu,Mg,Al atom codoped with N) has been constructed and its electronic structure has been studied. The calculated results show that the formation energy of the Li2-N2 doping model is low and it is N-type. Through comparative analysis, it is found that the co-doped system of Na,K and N presents N-type, while the doped system shows P-type when M is Ag,Ba,Mg atom. The charge difference density of states shows that the covalent bond between N and N atoms will be formed when Li,Na,K codoped with N. The calculation results in this paper provide a theoretical reference for the design and application of doped Zn O photoelectric materials, and have a positive significance for the research and development of new photoelectric materials and devices.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.2;O483
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