本文選題：ZnMgO薄膜　切入點：氧空位　出處：《山西師范大學》2015年碩士論文

【摘要】：稀磁半導體材料由于其在未來半導體自旋電子學器件中的巨大潛在應用而受到人們的廣泛關(guān)注。近幾年，3d過渡金屬元素摻雜的具有室溫鐵磁性的寬禁帶氧化物半導體材料取得了很大進展，但其磁性來源卻一直存在較大爭議。最近，非磁性元素摻雜或無摻雜氧化物薄膜的d0鐵磁性引起人們的研究興趣，在這類材料中，不需要考慮第二相磁性雜質(zhì)對材料磁性的貢獻，可以更好地研究材料缺陷等因素對氧化物薄膜磁性的影響。本論文利用脈沖激光沉積系統(tǒng)，在不同的沉積條件下制備出了多個系列的ZnMgO薄膜樣品，研究了沉積氧壓及靶材中Mg含量的改變對薄膜結(jié)構(gòu)、磁性及光學帶隙的影響；并在相同沉積氧壓下探究了ZnMgO薄膜中氧空位、磁性與帶隙間的關(guān)系；另外還研究了不同沉積氧壓下制備的ZnMgCoO薄膜，，分析了沉積氧壓對薄膜結(jié)構(gòu)、磁學及光學性質(zhì)的影響。主要研究內(nèi)容如下： （1）我們選用脈沖激光沉積系統(tǒng)，在雙拋Al2O3(0001)基片上制備了一系列沉積氧壓遞變的Zn0.9Mg0.1O薄膜，發(fā)現(xiàn)隨沉積氧壓的增大，薄膜沿c軸方向的晶格常數(shù)不斷減小，對應的ZnO（002）峰逐漸向右偏移；而薄膜的帶隙則隨著沉積氧壓的增大而減小，這是由于薄膜中的Mg含量與沉積氧壓成反比；Zn0.9Mg0.1O薄膜材料的室溫飽和磁化強度則呈現(xiàn)出一種先增大后減小的趨勢，這可能與氧空位的濃度變化有關(guān)，本底真空生長的薄膜中缺陷種類較多，使得氧空位的有效濃度降低，影響了材料的磁性，在沉積氧壓增加的過程中，氧空位濃度會出現(xiàn)一個最大值，然后逐漸減小。我們在相同的制備條件下沉積了一系列Zn0.85Mg0.15O薄膜，并得到了與上述變化規(guī)律一致的實驗結(jié)果。此外，我們還選用Zn0.9Mg0.1O合金陶瓷靶材，在完全相同的沉積氧壓下制備了一系列Zn0.9Mg0.1O薄膜材料，研究發(fā)現(xiàn)氧空位可以起到同時調(diào)控薄膜磁性及光學帶隙的作用。薄膜中氧空位濃度越大，磁性越強，光學帶隙越窄。 （2）我們選用純ZnO陶瓷靶材以及由固相反應法制得的Zn0.95Mg0.05O、Zn0.9Mg0.1O和Zn0.85Mg0.15O合金陶瓷靶材，分別在本底真空和20mTorr氧壓下，以雙拋Al2O3(0001)基片為襯底制備了多種Zn1-XMgXO薄膜樣品，發(fā)現(xiàn)隨靶材中Mg含量的增加，薄膜ZnO(002)峰對應的2θ值不斷增大，這是由于Mg2+半徑小于Zn2+半徑所致；由于MgO的帶隙遠大于ZnO的帶隙，薄膜中的Mg含量越高，薄膜的帶隙也越大；然而，隨Mg摩爾百分比（X）的增加，Zn1-XMgXO薄膜的室溫飽和磁化強度呈現(xiàn)出先升高后降低的趨勢，且在X=0.10時達到最大，導致這種變化規(guī)律的原因可能是由于Mg的加入使ZnO晶體中出現(xiàn)更多與室溫鐵磁性相關(guān)的點缺陷，而當Mg的含量過多時，ZnO晶體中的缺陷種類繁復，以致有效缺陷濃度降低所致。 （3）選用脈沖激光沉積技術(shù)以雙拋Al2O3(0001)基片為襯底，在不同的沉積氧壓下制備了過渡金屬Co摻雜的Zn0.85Mg0.10Co0.05O薄膜，發(fā)現(xiàn)隨沉積氧壓的增大，薄膜ZnO（002）峰逐漸向右偏移，帶隙逐漸減小，室溫鐵磁性先升高后減低，與Zn0.9Mg0.1O和Zn0.85Mg0.15O薄膜的變化規(guī)律相同。
[Abstract]:In recent years , it is not necessary to consider the contribution of the second - phase magnetic impurities to the magnetic properties of oxide films .
The relationship between oxygen vacancy , magnetic and gap in ZnMgO thin films was investigated under the same oxygen pressure .
The effects of deposition oxygen pressure on film structure , magnetic properties and optical properties were studied . The main research contents were as follows :

( 1 ) We chose a pulsed laser deposition system to prepare a series of Zn0.9Mg0 . 1O films deposited with oxygen pressure on a double - cast Al2O3 ( 0001 ) substrate . It was found that the lattice constant of the film in the direction of the c - axis decreased with the increase of the deposition oxygen pressure , and the corresponding ZnO ( 002 ) peak shifted to the right ;
The band gap of the film decreases with the increase of the deposition oxygen pressure , because the Mg content in the film is inversely proportional to the deposition oxygen pressure ;
A series of Zn0 . 85Mg0 . 15O films were deposited under the same conditions .

( 2 ) We chose pure ZnO ceramic target and Zn0 . 95Mg0 . 05O , Zn0 . 9Mg0 . 1O and Zn0 . 85Mg0 . 15O alloy ceramic target prepared by solid phase reaction .
As the band gap of MgO is much larger than that of ZnO , the higher the Mg content in the film , the larger the band gap of the film .
However , with the increase of Mg mole percentage ( X ) , the room temperature saturation magnetization of the Zn1 - XMgXO thin film exhibits a tendency to decrease first and reach the maximum at X = 0.10 , which may cause more point defects in the ZnO crystal due to the addition of Mg , and when the content of Mg is too much , the type of defects in the ZnO crystal is complex , so that the effective defect concentration is reduced .

( 3 ) The Zn0 . 85Mg0 . 10Co0 . 05O films doped with the transition metal Co were prepared by pulsed laser deposition . The ZnO ( 002 ) peak was shifted to the right with increasing oxygen pressure , the band gap was gradually decreased , the room temperature ferromagnetism increased first and then decreased , which was the same as that of Zn0 . 9Mg0 . 1O and Zn0 . 85Mg0 . 15O films .

【學位授予單位】：山西師范大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：O649;TB383.2

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本文編號：1695151