強(qiáng)磁場調(diào)控ZnO稀磁半導(dǎo)體結(jié)構(gòu)與性能研究
發(fā)布時間：2019-07-08 18:34
【摘要】：稀磁半導(dǎo)體是指半導(dǎo)體中由磁性離子部分替代非磁性陽離子所形成的新型半導(dǎo)體。通過同時操控電子電荷和自旋兩個自由度,稀磁半導(dǎo)體在自旋電子與磁性材料器件上具有巨大的潛在應(yīng)用,因而逐漸受到關(guān)注。稀磁半導(dǎo)體的實(shí)際應(yīng)用關(guān)鍵在于使其具備室溫鐵磁性。在理論計(jì)算的引導(dǎo)下,過渡元素?fù)诫s的ZnO成為最受關(guān)注的稀磁半導(dǎo)體材料。關(guān)于過渡元素?fù)诫sZnO的研究迅速成為包括凝聚態(tài)物理、磁性材料、自旋材料等領(lǐng)域的熱點(diǎn)。本論文以過渡元素?fù)诫sZnO稀磁半導(dǎo)體為研究對象,結(jié)合XRD,SEM,TEM,Raman,PL,UV-Vis,XPS,VSM和PPMS等材料學(xué)分析測試方法研究了ZnO稀磁半導(dǎo)體鐵磁性來源問題。通過在水熱法中引入強(qiáng)磁場,進(jìn)一步探討了脈沖強(qiáng)磁場影響過渡元素?fù)诫sZnO室溫鐵磁性的調(diào)控機(jī)理。本研究從以下三個層面展開:首先,采用水熱法在不同實(shí)驗(yàn)條件下制備了1%Cr-1%Ni共摻雜ZnO,研究了水熱法下ZnO稀磁半導(dǎo)體的生長習(xí)性,摸清了實(shí)驗(yàn)過程中各化學(xué)和物理參數(shù)對ZnO稀磁半導(dǎo)體微觀形貌和磁學(xué)性能的影響規(guī)律。化學(xué)參數(shù)中的鋅/堿源濃度和滴加順序微弱地影響晶粒尺寸,對磁學(xué)性能的影響不大;而pH值則通過調(diào)制前驅(qū)體絡(luò)合物電荷類型直接決定了1%Cr-1%Ni共摻雜ZnO晶體生長形貌;物理參數(shù)中反應(yīng)溫度和反應(yīng)釜壓力主要影響晶體的形核階段,對晶體形貌作用較大。反應(yīng)時間和反應(yīng)介質(zhì)主要改變晶體的生長階段,對晶體的長大有微弱的促進(jìn)或抑制。其次,研究了過渡元素共摻雜和摻雜量對ZnO稀磁半導(dǎo)體磁學(xué)性能的作用。在Cr-Ni摻雜體系中共摻雜有效提高了樣品的鐵磁性能,摻雜量的增加導(dǎo)致更多近鄰離子對,增強(qiáng)的反鐵磁交換作用反而減弱了樣品的鐵磁性能;而Fe-Mn摻雜體系中共摻雜則直接促使了樣品從單一摻雜(1%Fe-1%Fe/1%Mn-1%Mn)的順磁性轉(zhuǎn)變?yōu)楣矒诫s(1%Fe-1%Mn)的室溫鐵磁性;過渡元素共摻雜對ZnO稀磁半導(dǎo)體磁學(xué)性能的作用不僅是簡單的線性疊加作用,而且存在明顯的協(xié)同效應(yīng)。最后,在水熱法過程中施加脈沖磁場,研究了強(qiáng)磁場對1%Cr-1%Ni、1%Cr-1%Mn和2%Ni-2%Al共摻雜ZnO稀磁半導(dǎo)體微觀結(jié)構(gòu)和磁學(xué)性能的影響。脈沖磁場對水熱法生長的ZnO晶體形貌影響并不顯著,而且這種影響也會根據(jù)摻雜元素的改變而表現(xiàn)出不同的趨勢。脈沖磁場對過渡元素?fù)诫sZn O的磁學(xué)性能影響顯著,可以誘導(dǎo)室溫鐵磁性能,這種影響根據(jù)摻雜體系可以劃分為兩類。其一,在Cr、Ni摻雜體系中,脈沖磁場可以有效提高ZnO晶體中氧空位缺陷的濃度,提升室溫鐵磁性能;其二,在Mn摻雜體系中,脈沖磁場可以直接促使ZnO晶體中鋅空位缺陷的生成,導(dǎo)致室溫鐵磁性的出現(xiàn)。前者符合J.M.D Coey對于束縛磁極子理論的闡述和Sato對ZnO稀磁半導(dǎo)體的第一性原理的計(jì)算,后者與Dietl關(guān)于Mn摻雜ZnO計(jì)算結(jié)果吻合。Cr/Ni摻雜有利于ZnO中氧空位的形成,而Mn摻雜則為鋅空位缺陷的形成提供了條件,脈沖磁場的添加擴(kuò)大化了這種極性偏差。與已有的文獻(xiàn)報道相比,本研究不僅采用水熱法成功制備出了具有本征室溫鐵磁性的不同過渡元素?fù)诫sZnO稀磁半導(dǎo)體,明確了共摻雜對ZnO鐵磁性能的提升作用,而且發(fā)現(xiàn)強(qiáng)磁場調(diào)控不同過渡元素?fù)诫sZnO微觀結(jié)構(gòu)與性能的機(jī)理各異。
文內(nèi)圖片：![自旋器件技術(shù)樹和它們的潛在應(yīng)用[1]](http://image.cnki.net/getimage.ashx?id=1016285084.nh0001)
圖片說明：自旋器件技術(shù)樹和它們的潛在應(yīng)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.
【學(xué)位授予單位】：上海大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TN304.21
，
本文編號：2511790
文內(nèi)圖片：
圖片說明：自旋器件技術(shù)樹和它們的潛在應(yīng)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.
【學(xué)位授予單位】：上海大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TN304.21
，
本文編號：2511790
本文鏈接：http://sikaile.net/shoufeilunwen/xxkjbs/2511790.html
最近更新
教材專著
