强磁场调控ZnO稀磁半导体结构与性能研究
发布时间：2019-07-08 18:34
【摘要】：稀磁半导体是指半导体中由磁性离子部分替代非磁性阳离子所形成的新型半导体。通过同时操控电子电荷和自旋两个自由度,稀磁半导体在自旋电子与磁性材料器件上具有巨大的潜在应用,因而逐渐受到关注。稀磁半导体的实际应用关键在于使其具备室温铁磁性。在理论计算的引导下,过渡元素掺杂的ZnO成为最受关注的稀磁半导体材料。关于过渡元素掺杂ZnO的研究迅速成为包括凝聚态物理、磁性材料、自旋材料等领域的热点。本论文以过渡元素掺杂ZnO稀磁半导体为研究对象,结合XRD,SEM,TEM,Raman,PL,UV-Vis,XPS,VSM和PPMS等材料学分析测试方法研究了ZnO稀磁半导体铁磁性来源问题。通过在水热法中引入强磁场,进一步探讨了脉冲强磁场影响过渡元素掺杂ZnO室温铁磁性的调控机理。本研究从以下三个层面展开:首先,采用水热法在不同实验条件下制备了1%Cr-1%Ni共掺杂ZnO,研究了水热法下ZnO稀磁半导体的生长习性,摸清了实验过程中各化学和物理参数对ZnO稀磁半导体微观形貌和磁学性能的影响规律。化学参数中的锌/碱源浓度和滴加顺序微弱地影响晶粒尺寸,对磁学性能的影响不大;而pH值则通过调制前驱体络合物电荷类型直接决定了1%Cr-1%Ni共掺杂ZnO晶体生长形貌;物理参数中反应温度和反应釜压力主要影响晶体的形核阶段,对晶体形貌作用较大。反应时间和反应介质主要改变晶体的生长阶段,对晶体的长大有微弱的促进或抑制。其次,研究了过渡元素共掺杂和掺杂量对ZnO稀磁半导体磁学性能的作用。在Cr-Ni掺杂体系中共掺杂有效提高了样品的铁磁性能,掺杂量的增加导致更多近邻离子对,增强的反铁磁交换作用反而减弱了样品的铁磁性能;而Fe-Mn掺杂体系中共掺杂则直接促使了样品从单一掺杂(1%Fe-1%Fe/1%Mn-1%Mn)的顺磁性转变为共掺杂(1%Fe-1%Mn)的室温铁磁性;过渡元素共掺杂对ZnO稀磁半导体磁学性能的作用不仅是简单的线性叠加作用,而且存在明显的协同效应。最后,在水热法过程中施加脉冲磁场,研究了强磁场对1%Cr-1%Ni、1%Cr-1%Mn和2%Ni-2%Al共掺杂ZnO稀磁半导体微观结构和磁学性能的影响。脉冲磁场对水热法生长的ZnO晶体形貌影响并不显著,而且这种影响也会根据掺杂元素的改变而表现出不同的趋势。脉冲磁场对过渡元素掺杂Zn O的磁学性能影响显著,可以诱导室温铁磁性能,这种影响根据掺杂体系可以划分为两类。其一,在Cr、Ni掺杂体系中,脉冲磁场可以有效提高ZnO晶体中氧空位缺陷的浓度,提升室温铁磁性能;其二,在Mn掺杂体系中,脉冲磁场可以直接促使ZnO晶体中锌空位缺陷的生成,导致室温铁磁性的出现。前者符合J.M.D Coey对于束缚磁极子理论的阐述和Sato对ZnO稀磁半导体的第一性原理的计算,后者与Dietl关于Mn掺杂ZnO计算结果吻合。Cr/Ni掺杂有利于ZnO中氧空位的形成,而Mn掺杂则为锌空位缺陷的形成提供了条件,脉冲磁场的添加扩大化了这种极性偏差。与已有的文献报道相比,本研究不仅采用水热法成功制备出了具有本征室温铁磁性的不同过渡元素掺杂ZnO稀磁半导体,明确了共掺杂对ZnO铁磁性能的提升作用,而且发现强磁场调控不同过渡元素掺杂ZnO微观结构与性能的机理各异。
文内图片：![自旋器件技术树和它们的潜在应用[1]](http://image.cnki.net/getimage.ashx?id=1016285084.nh0001)
图片说明：自旋器件技术树和它们的潜在应用[1]
[Abstract]:The rare-magnetic semiconductor refers to a new type of semiconductor formed by replacing the non-magnetic cation with the magnetic ion part in the semiconductor. By simultaneously controlling both the electronic charge and the spin two degrees of freedom, the rare-magnetic semiconductor has a great potential application on the spin-electron and magnetic material devices and is therefore gradually concerned. The key to the practical application of the thin-magnetic semiconductor is to have the ferromagnetism at room temperature. Under the guidance of the theoretical calculation, the doped ZnO of the transition element becomes the most important rare-magnetic semiconductor material. The research on the doped ZnO of the transition element rapidly becomes a hot spot in the fields of condensed matter physics, magnetic material, spin material and so on. The ferromagnetic source of ZnO thin-magnetic semiconductor is studied by means of XRD, SEM, TEM, Raman, PL, UV-Vis, XPS, VSM and PPMS. By introducing a strong magnetic field in the hydrothermal method, the regulation mechanism of the transition element doped ZnO at room temperature is further discussed. In this study, the growth habit of ZnO thin-magnetic semiconductor under hydrothermal method was studied by using a hydrothermal method to prepare 1% Cr-1% Ni co-doped ZnO under different experimental conditions. The effects of chemical and physical parameters on the micro-morphology and magnetic properties of the ZnO thin-magnetic semiconductor were investigated. The concentration of zinc/ alkali source and the order of drop in the chemical parameters influence the grain size, and the effect on the magnetic properties is not small; and the pH value directly determines the crystal morphology of 1% Cr-1% Ni co-doped ZnO crystal by modulating the charge type of the precursor complex. The reaction temperature and reactor pressure in the physical parameters mainly influence the nucleation stage of the crystal, and the effect on the crystal morphology is large. The reaction time and the reaction medium mainly change the growth stage of the crystal, and the growth of the crystal is weakly promoted or inhibited. Secondly, the effect of the co-doping and doping of the transition element on the magnetic properties of the ZnO thin-magnetic semiconductor is studied. the doping of the Cr-Ni doping system effectively improves the ferromagnetic energy of the sample, the increase of the doping amount leads to more nearest neighbor ion pairs, and the enhanced anti-ferromagnetic exchange effect is only weakened by the ferromagnetic energy of the sample; and the co-doping of the Fe-Mn doping system directly causes the paramagnetic transition of the sample from the single doping (1% Fe-1% Fe/1% Mn-1% Mn) to the room temperature ferromagnetism of the co-doping (1% Fe-1% Mn); the effect of the co-doping of the transition element on the magnetic properties of the ZnO thin-magnetic semiconductor is not only a simple linear superposition effect, And there is a clear synergistic effect. Finally, the effect of strong magnetic field on microstructure and magnetic properties of 1% Cr-1% Ni,1% Cr-1% Mn and 2% Ni-2% Al co-doped ZnO thin-magnetic semiconductor was studied by applying a pulsed magnetic field during the hydrothermal process. The effect of the pulsed magnetic field on the morphology of the ZnO crystal grown by hydrothermal method is not significant, and the effect can also show different trends according to the change of the doping elements. The influence of the pulsed magnetic field on the magnetic properties of the doped Zn O of the transition element can induce the ferromagnetic energy at room temperature, which can be divided into two types according to the doping system. First, in the Cr and Ni doping system, the pulse magnetic field can effectively improve the concentration of oxygen vacancy defects in the ZnO crystal and improve the ferromagnetism energy of the room temperature; secondly, in the Mn doping system, the pulse magnetic field can directly cause the generation of the zinc vacancy defects in the ZnO crystal, leading to the occurrence of the ferromagnetism at the room temperature. The former is in accordance with the theory of J. M. D Coy for the theory of bound magnetic pole, and Sato's calculation of the first principle of ZnO thin-magnetic semiconductors, which is in agreement with the results of Dietl's calculation of Mn-doped ZnO. The doping of Cr/ Ni is beneficial to the formation of oxygen vacancies in ZnO, and the doping of Mn provides the condition for the formation of zinc vacancy. Compared with the existing literature, the present study not only successfully prepared a different transition element doped ZnO thin-magnetic semiconductor with intrinsic room temperature ferromagnetism, but also made clear the improvement of the co-doping on the ferromagnetism of ZnO. It is also found that the mechanism of different transition element-doped ZnO microstructure and performance is different.
【学位授予单位】：上海大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN304.21
，
本文编号：2511790
文内图片：
图片说明：自旋器件技术树和它们的潜在应用[1]
[Abstract]:The rare-magnetic semiconductor refers to a new type of semiconductor formed by replacing the non-magnetic cation with the magnetic ion part in the semiconductor. By simultaneously controlling both the electronic charge and the spin two degrees of freedom, the rare-magnetic semiconductor has a great potential application on the spin-electron and magnetic material devices and is therefore gradually concerned. The key to the practical application of the thin-magnetic semiconductor is to have the ferromagnetism at room temperature. Under the guidance of the theoretical calculation, the doped ZnO of the transition element becomes the most important rare-magnetic semiconductor material. The research on the doped ZnO of the transition element rapidly becomes a hot spot in the fields of condensed matter physics, magnetic material, spin material and so on. The ferromagnetic source of ZnO thin-magnetic semiconductor is studied by means of XRD, SEM, TEM, Raman, PL, UV-Vis, XPS, VSM and PPMS. By introducing a strong magnetic field in the hydrothermal method, the regulation mechanism of the transition element doped ZnO at room temperature is further discussed. In this study, the growth habit of ZnO thin-magnetic semiconductor under hydrothermal method was studied by using a hydrothermal method to prepare 1% Cr-1% Ni co-doped ZnO under different experimental conditions. The effects of chemical and physical parameters on the micro-morphology and magnetic properties of the ZnO thin-magnetic semiconductor were investigated. The concentration of zinc/ alkali source and the order of drop in the chemical parameters influence the grain size, and the effect on the magnetic properties is not small; and the pH value directly determines the crystal morphology of 1% Cr-1% Ni co-doped ZnO crystal by modulating the charge type of the precursor complex. The reaction temperature and reactor pressure in the physical parameters mainly influence the nucleation stage of the crystal, and the effect on the crystal morphology is large. The reaction time and the reaction medium mainly change the growth stage of the crystal, and the growth of the crystal is weakly promoted or inhibited. Secondly, the effect of the co-doping and doping of the transition element on the magnetic properties of the ZnO thin-magnetic semiconductor is studied. the doping of the Cr-Ni doping system effectively improves the ferromagnetic energy of the sample, the increase of the doping amount leads to more nearest neighbor ion pairs, and the enhanced anti-ferromagnetic exchange effect is only weakened by the ferromagnetic energy of the sample; and the co-doping of the Fe-Mn doping system directly causes the paramagnetic transition of the sample from the single doping (1% Fe-1% Fe/1% Mn-1% Mn) to the room temperature ferromagnetism of the co-doping (1% Fe-1% Mn); the effect of the co-doping of the transition element on the magnetic properties of the ZnO thin-magnetic semiconductor is not only a simple linear superposition effect, And there is a clear synergistic effect. Finally, the effect of strong magnetic field on microstructure and magnetic properties of 1% Cr-1% Ni,1% Cr-1% Mn and 2% Ni-2% Al co-doped ZnO thin-magnetic semiconductor was studied by applying a pulsed magnetic field during the hydrothermal process. The effect of the pulsed magnetic field on the morphology of the ZnO crystal grown by hydrothermal method is not significant, and the effect can also show different trends according to the change of the doping elements. The influence of the pulsed magnetic field on the magnetic properties of the doped Zn O of the transition element can induce the ferromagnetic energy at room temperature, which can be divided into two types according to the doping system. First, in the Cr and Ni doping system, the pulse magnetic field can effectively improve the concentration of oxygen vacancy defects in the ZnO crystal and improve the ferromagnetism energy of the room temperature; secondly, in the Mn doping system, the pulse magnetic field can directly cause the generation of the zinc vacancy defects in the ZnO crystal, leading to the occurrence of the ferromagnetism at the room temperature. The former is in accordance with the theory of J. M. D Coy for the theory of bound magnetic pole, and Sato's calculation of the first principle of ZnO thin-magnetic semiconductors, which is in agreement with the results of Dietl's calculation of Mn-doped ZnO. The doping of Cr/ Ni is beneficial to the formation of oxygen vacancies in ZnO, and the doping of Mn provides the condition for the formation of zinc vacancy. Compared with the existing literature, the present study not only successfully prepared a different transition element doped ZnO thin-magnetic semiconductor with intrinsic room temperature ferromagnetism, but also made clear the improvement of the co-doping on the ferromagnetism of ZnO. It is also found that the mechanism of different transition element-doped ZnO microstructure and performance is different.
【学位授予单位】：上海大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN304.21
，
本文编号：2511790
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