（V,Cu,Fe）单掺ZnO电子结构和磁光性能影响的研究

发布时间：2018-01-18 06:32

本文关键词：（V,Cu,Fe）单掺ZnO电子结构和磁光性能影响的研究　出处：《内蒙古工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：Zn O是一种新型Ⅱ-Ⅵ族化合物,具有无毒无污染、原料丰富易得、制备成本低、热稳定性和化学稳定性高等优点。同时,在室温下,Zn O还具有3.37e V的直接宽禁带,60me V的高激子束缚能。因此,Zn O已在气体传感器、太阳能电池、压敏电阻、液晶显示器、紫外半导体激光器、透明导电薄膜以及稀磁半导体等方面具有广泛的应用前景。研究发现,通过(V、Cu、Fe)掺杂过渡金属可改进和完善Zn O的磁光性能的影响,尤其是合理解释了实验中有争议的掺杂体系Zn O吸收光谱分布的影响。本文利用第一性原理,采用GGA+U的方法,对未掺杂Zn O及掺杂Zn O进行模拟计算,重点研究了过渡元素(V、Cu、Fe)掺杂对Zn O的电子结构和磁光性能的影响,具体创新点如下:首先,研究了Zn1-xVx O(x=0、0.0417和0.0625)三种超胞的电子结构、磁性和吸收光谱的影响。计算结果表明,随着V掺杂量的增加,掺杂越容易、磁性越增强、体系共价键越增强、离子键越减弱、总能量越降低、体系结构越稳定。同时,掺杂体系产生多余的电子越增加、电荷之间的相互作用越增强、Burstein-Moss效应越明显、使体系吸收带边越向低能级方向移动、最小光学带隙越变宽、吸收光谱蓝移越增强。其次,Cu替位掺杂Zn O体系吸收光谱蓝移和红移两种相反的实验结果均有文献报道。为解决这个矛盾,研究了未掺杂Zn O、Zn0.9687Cu0.0313O、Zn0.9375Cu0.0625O和Zn32Cu O32超胞的电子结构和吸收光谱。计算结果表明,Cu替位掺杂量越增加,总能量越增加、掺杂体系越不稳定、形成能越增加、掺杂越难、掺杂体系的导带底向低能级方向移动、而价带顶的位置几乎不动、带隙宽度越变窄、吸收光谱越红移。同时,研究发现,Cu间隙掺杂体系的带隙和吸收光谱变化趋势与替位掺杂体系的相反。再者,研究了Fe高掺杂浓度对Zn O磁光性能的影响。对未掺杂Zn O、Zn0.9687Fe0.0313O和Zn0.9583Fe0.0417O超胞的最小光学带隙和吸收光谱进行了分析。计算结果表明,在Fe掺杂量为1.563~2.083at%的范围内,Fe掺杂量越增加、体系的价带顶向低能级方向移动、最小光学带隙越宽,吸收光谱蓝移越显著。最后,考虑到Zn O的单极性结构,对四种不同空间有序占位双掺Fe原子组态Zn14Fe2O16进行磁性的研究。结果表明,这些组态具有铁磁有序的基态,铁磁稳定性是通过双交换作用实现的,研究发现双掺Fe原子偏沿c轴方向越近、铁磁性越增强、高自旋极化率越高、居里温度越高、预测能够超过室温。Fe掺杂有利于提高Zn O体系的铁磁性,有望获得稳定性高、居里温度高、自旋极化率越高的稀磁半导体材料。
[Abstract]:Zn O is a new type of II-VI compounds, has no pollution, abundant raw material, low production cost, high thermal stability and chemical stability advantages. At the same time, at room temperature, direct wide bandgap Zn O also has 3.37e V, 60me high exciton binding energy of V. Therefore, Zn O in solar cells, gas sensors, varistors, liquid crystal display, UV semiconductor laser, and has wide application prospect and transparent conductive films of diluted magnetic semiconductors and so on. The study found that the (V, Cu, Fe) doped with transition metals can improve and perfect Zn O magneto-optical properties, especially the reasonable explain the Zn doping O controversial absorption spectrum were discussed in the experiment. By using the first principle, use GGA+U method to simulate the undoped Zn and O doped Zn O, focusing on the transition elements (V, Cu, Fe) doped Zn O electronic structure Optical and magnetic properties, the main innovations are as follows: firstly, the research of Zn1-xVx O (x=0,0.0417 and 0.0625) three kinds of electronic structure of the super cell, the effects of the magnetic and absorption spectra. The results show that with the increase of V doping and doping more easily, more magnetic enhancement system of covalent bond is enhanced, ion the key is weakened, the total energy is reduced, the system structure is more stable. At the same time, doping system of excess electron increases, the interaction between the charge is increased, the Burstein-Moss effect was more obvious, make the system more absorption edge to the low level moves, the minimum optical band gap became more and more wide, a blue shift in the absorption spectra enhanced. Secondly, substitutional Cu doped Zn O system absorption spectra of blue and red shift of two opposite results were reported in the literature. In order to solve this contradiction, Zn0.9687Cu0.0313O of undoped Zn, O, Zn0.9375Cu0.0625O and Zn32Cu electronic O32 ultra cell The structure and absorption spectrum. The results showed that Cu substitution doping amount increases, the total energy increases, the doped system is not stable, the formation energy increases, doping more difficult, the conduction band doped bottom to the low level direction, and the top of the valence band position almost motionless, the band gap width is narrow, absorption spectrum is red shifted. At the same time, the study found that the band gap of Cu doped gap and the absorption spectrum changes with the substitutional doping system instead. Furthermore, the effects of Fe doping concentration on the properties of Zn O magnetic light. For Zn doped O, Zn0.9687Fe0.0313O and Zn0.9583Fe0.0417O of the super cell optical band gap and the minimum the analysis of absorption spectra. The results show that the Fe doping concentration range of 1.563~2.083at%, Fe doping system increases, the top of the valence band shifts to lower level direction, the minimum optical band gap is wide, a blue shift in the absorption spectra is more significant. Finally, considering Z Unipolar structure of n O, a study of double doped Fe magnetic ordered atomic configuration Zn14Fe2O16 accounted for four different kinds of space. The results show that the ground state configuration has ordered ferromagnetic, ferromagnetic stability is achieved through double exchange interaction, the study found that double doped Fe atom along the c axis near the iron the stronger the magnetic, high spin polarization rate is high, the Curie temperature is high, can predict over room temperature.Fe doping is beneficial to improve the ferromagnetism in Zn O system, is expected to achieve high stability, high Curie temperature, the higher the rate of spin polarization of the diluted magnetic semiconductors.

【学位授予单位】：内蒙古工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.25

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