Co、Mn掺杂ZnO稀磁半导体特性研究

发布时间：2018-04-18 08:25

  本文选题：稀磁半导体 + 自旋电子器件　； 参考：《江苏大学》2017年硕士论文

【摘要】：自旋电子器件由于具有体积小,速度快,非易失性等优点,可以极大提高信息的处理速度。稀磁半导体作为自旋电子器件中的关键材料,目前已经引起了电子学、物理学及材料科学等多学科研究者的关注。ZnO基稀磁半导体由于具有性质稳定、原料丰富、可以实现高浓度掺杂等优点,并且在光、电、磁等领域存在众多优异性质,已经成为了稀磁半导体研究的热门领域,并取得了一定的进展。但在众多的理论计算和实验研究成果中,仍然存在很多亟需解决的问题,如实验重复性差、居里温度低、磁性起源机理不明确等。为寻求具有高居里温度的ZnO基稀磁半导体,本文采用了基于密度泛函理论(DFT)的第一性原理研究方法,计算并讨论了Co、Mn单掺杂和共掺杂ZnO基稀磁半导体的磁稳定性和磁性起源机理,并研究了非金属元素和本征缺陷的引入对Co-Mn共掺杂ZnO的影响。得到研究结果如下:(1)分别构建了2×2×2的Co单掺杂ZnO和Mn单掺杂ZnO超晶胞模型,对它们在五种不同掺杂位置下的构型进行计算和分析。结果表明:Co单掺杂ZnO和Mn单掺杂ZnO都不具有室温铁磁性。系统的磁稳定性与杂质元素的掺杂位置有很大关系,其中Co掺杂ZnO在两种构型下表现出铁磁性,另外三种构型下表现出反铁磁;Mn掺杂Zn O五种构型均表现出反铁磁性。从能量角度来看,Co掺杂ZnO和Mn掺杂ZnO均趋向于紧密构型,即当掺杂原子间距离较近时,体系基态能量更低、结构更稳定。(2)根据掺杂位置的分析结果,构建了紧密构型下的Co-Mn共掺杂ZnO模型。对其磁性和电子特性的计算和研究表明:相比于单掺杂体系,Co-Mn共掺杂ZnO表现出了稳定的铁磁性,并且具有远高于室温的居里温度。其磁性起源主要是Co和Mn的3d电子通过邻近O原子发生的交换作用。(3)为研究实际制备中常见的空位缺陷和杂质对ZnO基稀磁半导体的影响,本文在Co-Mn共掺杂ZnO体系中引入了空位及非金属元素的掺杂缺陷。结果显示,当Co-Mn共掺杂ZnO中引入O缺陷、C元素和N元素后,体系从铁磁稳定转变为反铁磁稳定。从而表明在Co-Mn共掺杂ZnO中,O缺陷、C元素和N元素的引入不利于形成室温铁磁体,在制备过程中要避免这些杂质的产生。Zn空位的引入对于Co-Mn共掺杂ZnO的磁性和居里温度有明显的提高。具体表现在:增强了邻近O原子和Co原子的磁矩,但对Mn原子的磁矩略有削弱。体系自旋劈裂的产生除Co-3d、Mn-3d电子的共同作用外,Zn空位的引入也大大加强了O-2p在费米能级处的自旋劈裂。
[Abstract]:Spin electronic devices can greatly improve the processing speed of information because of its advantages of small volume, high speed and nonvolatile.As a key material in spin electronic devices, dilute magnetic semiconductors have attracted the attention of many researchers in electronics, physics and material science. ZnO based diluted magnetic semiconductors have stable properties and abundant raw materials.High concentration doping can be realized, and there are many excellent properties in the fields of light, electricity, magnetism and so on. It has become a hot field in the research of dilute magnetic semiconductor, and has made some progress.However, in many theoretical and experimental results, there are still many problems that need to be solved, such as poor repeatability, low Curie temperature, unclear magnetic origin mechanism and so on.In order to search for ZnO based diluted magnetic semiconductors with high Curie temperature, the first principle research method based on density functional theory (DFT) is used in this paper.The magnetic stability and magnetic origin mechanism of Co-Mn mono-doped and co-doped ZnO based diluted magnetic semiconductors were calculated and discussed. The influence of the introduction of nonmetallic elements and intrinsic defects on Co-Mn co-doped ZnO was studied.The results are as follows: (1) 2 脳 2 脳 2 Co mono-doped ZnO and mn mono-doped ZnO supercell models are constructed, and their configurations at five different doping positions are calculated and analyzed.The results show that neither ZnO nor mn mono-doped ZnO have room temperature ferromagnetism.The magnetic stability of the system is closely related to the doping position of impurity elements. Co- doped ZnO exhibits ferromagnetism in two configurations, and the other three show antiferromagnetic properties in all of the five Zn-doped Zn-O configurations.From the point of view of energy, both Co doped ZnO and mn doped ZnO tend to be compact, that is, when the doping atoms are close, the ground state energy is lower and the structure is more stable.The Co-Mn co-doped ZnO model with compact configuration was constructed.The calculation and study of the magnetic and electronic properties show that the codoped ZnO exhibits stable ferromagnetism and is much higher than the Curie temperature at room temperature.Its magnetic origin is mainly due to the exchange of 3D electrons of Co and mn through adjacent O atoms. The effect of vacancy defects and impurities on ZnO based diluted magnetic semiconductors is studied.Vacancy and nonmetallic doping defects were introduced into Co-Mn co-doped ZnO system.The results show that the system changes from ferromagnetic stability to antiferromagnetic stability when O defect C and N elements are introduced into Co-Mn co-doped ZnO.It is shown that the introduction of C and N elements in Co-Mn co-doped ZnO is not conducive to the formation of room temperature ferromagnets.In the process of preparation, it is necessary to avoid the introduction of these impurities. Zn vacancies can obviously improve the magnetic properties and Curie temperature of Co-Mn co-doped ZnO.The results show that the magnetic moment of the adjacent O and Co atoms is enhanced, but the magnetic moment of mn atom is slightly weakened.In addition to the co-action of Co-3dGn-3d electrons, the introduction of Zn vacancy in the system also greatly strengthens the spin-splitting of O-2p at Fermi level.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN304

【参考文献】

相关期刊论文 前3条

1 侯清玉;李勇;赵春旺;;Al掺杂和空位对ZnO磁性影响的第一性原理研究[J];物理学报;2017年06期

2 肖振林;史力斌;;Cu掺杂ZnO铁磁性的研究[J];人工晶体学报;2011年01期

3 于威;张丽;张子才;杨丽华;滕晓云;张锦川;傅广生;;ZnO:Mn稀磁薄膜结构和铁磁特性分析[J];人工晶体学报;2009年03期

相关博士学位论文 前4条

1 张亚琳;电子关联效应对有机聚合物光电特性的影响[D];河北师范大学;2014年

2 陈灵娜;新型碳基纳米材料的电子结构和输运性质的理论研究[D];中南大学;2011年

3 梁培;掺杂ZnO稀磁半导体磁性的第一性原理计算[D];华中科技大学;2009年

4 张富春;3d过渡金属掺杂一维ZnO纳米材料磁光机理研究[D];中国科学院研究生院（西安光学精密机械研究所）;2009年

相关硕士学位论文 前10条

1 苟祖涛;Fe、Co掺杂ZnO稀磁半导体第一性原理研究[D];江苏大学;2016年

2 朱肖鹏;元素掺杂对ZnO晶体光电性能影响的第一性原理研究[D];燕山大学;2014年

3 吴瑞强;Ag掺杂ZnO稀磁特性的第一性原理研究[D];重庆师范大学;2014年

4 乔豫龙;钴掺杂氧化锌的第一性原理研究[D];哈尔滨理工大学;2014年

5 徐辉进;配位化合物的磁性机理研究[D];三峡大学;2011年

6 庄晋艳;氧化锌量子点结构、缺陷和发光性能的研究[D];天津理工大学;2009年

7 高慧霞;ZnO基稀磁半导体磁特性研究的第一性原理计算[D];河北大学;2009年

8 刘晓通;ZnO d~0铁磁性的研究[D];吉林大学;2009年

9 赵瑞斌;ZnO基稀磁半导体的光学和磁学性质[D];河北师范大学;2008年

10 肖斌;PLD法生长锂掺杂p型ZnO薄膜及其性质研究[D];浙江大学;2006年

，

本文编号：1767563