過渡金屬摻雜對於稀磁性氧化物薄膜之物性影響研究 = The study ...
國立高雄大學應用物理學系碩士班

 

  • 過渡金屬摻雜對於稀磁性氧化物薄膜之物性影響研究 = The study of transition metal doping effects on the physical properties of dilute magnetic oxide films
  • 紀錄類型: 書目-語言資料,印刷品 : 單行本
    並列題名: The study of transition metal doping effects on the physical properties of dilute magnetic oxide films
    作者: 李思賢,
    其他團體作者: 國立高雄大學
    出版地: [高雄市]
    出版者: 撰者;
    出版年: 民99[2010]
    面頁冊數: 181面圖,表 : 30公分;
    標題: 氧化鋅
    標題: ZnO
    電子資源: http://handle.ncl.edu.tw/11296/ndltd/49951201866351169137
    摘要註: 本論文研究利用射頻磁控共濺鍍法成長Zn1-xCrxO 與Zn1-xMnxO 稀磁性半導體薄膜,探討過渡金屬不同摻雜濃度對Zn1-xCrxO 與Zn1-xMnxO 薄膜在晶體結構、表面型態、光學性質、化學組成、電子結構、電性與磁性等物理性質的變化,希望能對於稀磁性半導體薄膜的磁性來源機制有所了解。鉻摻雜氧化鋅:由實驗結果得知,所有的薄膜都具有c 軸優先取向的wurtzite 結構,利用X光繞射與拉曼光譜儀的量測,顯示沒有任何鉻的氧化相,所有的薄膜都具有高的可見光穿透率,隨著鉻摻雜功率的增加,光學能隙有藍移的現象。由螢光光譜儀的檢測,純氧化鋅薄膜有鋅空缺與鋅間隙的存在。由X 光光電子能譜儀(XPS)的結果,一些二價的鉻離子(Cr2+)取代了鋅(zinc)的位置,當鉻摻雜濃度在0.026 以下時,薄膜存在二價與三價的鉻離子;但是,當鉻摻雜濃度達到0.046 以上時,薄膜中開始出現六價的鉻離子。使用四點探針進行電阻率的量測,所有的薄膜都具有較高的電阻率約為106 Ωcm。為了了解薄膜的磁性變化,進行了超導量子干涉儀(SQUID)的量測,當鉻摻雜濃度為0.026 時,幾乎沒有鐵磁訊號;但是,當摻雜濃度到達0.046 以上時,出現了鐵磁訊號。結果表明Cr-doped ZnO 薄膜的鐵磁性,可以用電荷轉移模型將其合理化解釋。退火熱處理後,所有薄膜的晶體結構變好。隨著鉻摻雜功率的增加,光學能隙有紅移的現象。由螢光光譜儀的檢測,純氧化鋅薄膜的缺陷變少。由X 光光電子能譜儀(XPS)的結果沒有看到六價鉻離子的存在。缺陷變少導致Zn1-xCrxO薄膜的順磁性增加且鐵磁性減弱。錳摻雜氧化鋅:在氬氣+氧氣或氬氣+氮氣的製程環境下成長Mn-doped ZnO 薄膜,利用X光繞射、掃瞄式電子顯微鏡、原子力顯微鏡、拉曼光譜儀、螢光光譜儀、紫外光-可見光分光光譜儀與X 光光電子能譜儀對薄膜進行檢測。由X 光繞射結果,所有的薄膜都具有c 軸優先取向的wurtzite 結構。由掃瞄式電子顯微鏡的觀察,晶粒尺寸隨著錳摻雜濃度增加而變小。拉曼光譜結果顯示,所有的薄膜沒有錳的金屬相或氧化相出現。薄膜在紫外光到可見光波段的穿透率都具有高的穿透率,利用Tauc’s 的方式計算出其光學能隙隨著錳的摻雜濃度增加而下降。由螢光光譜儀的結果顯示,3.2eV 的位置出現明顯且強烈的NBE(near-band-edge)訊號,錳的摻雜導致訊號強度下降。退火熱處理後,所有薄膜的晶體結構變好。隨著錳摻雜功率的增加,光學能隙產生改變。由螢光光譜儀的檢測,純氧化鋅薄膜的缺陷變少。由X 光光電子能譜儀(XPS)的結果,在氮氣環境下成長的Zn1-xMnxO 薄膜沒有看到四價錳離子的存在,導致薄膜鐵磁性非常微弱。缺陷變少導致Zn1-xMnxO 薄膜的順磁性增加且鐵磁性減弱。 In this thesis, we report effects of different doped concentration on the crystal structural, surface morphological, optical, chemical composition, electrical and magnetic properties of Cr-doped ZnO thin films. All of the film samples were deposited using the magnetron co-sputtering method. The aim of this work is to examine the possibility, as well as to the origin and mechanism of room- temperature ferromagnetic in Cr-doped ZnO films.Cr-doped ZnO:All of the films are highly c-axis-oriented wurtzite structures. No chromium metal or oxides were detected using x-ray diffraction or Raman spectroscopy. High visible transmittance (> 85% at λ= 550 nm) was maintained but a blue shift in optical band-gap was observed with increasing value of x. Photoluminescence spectra show that there are zinc interstitials and vacancies in the pure ZnO film, wherein a distinct paramagnetic response, as well as a weak ferromagnetic signal, persisted up to room temperature. For the Cr-doped ZnO films, some Cr ions substituted into Zn sites with a valency of 2+, whereas the remains are in a 3+ valence state when x <= 0.026 but in both 3+ and 6+ states when x >= 0.046. Ferromagnetism almost disappears at x = 0.026 but reappears at x >= 0.046. The results suggest that ferromagnetism in the Cr-doped ZnO films can be rationalized in terms of a charge-transfer model.Mn-doped ZnO:Comprehensive analysis techniques including x-ray diffraction, scanning electron microscopy, atomic force microscopy, Raman spectroscopy, photoluminescence, ultraviolet-visible spectrophotometer have been used to characterize the microstructure and optical properties of Mn-doped ZnO thin films deposited under the Ar + O2 or Ar + N2 growth atmosphere. The x-ray diffraction results showed that all films with wurtzite structure are preferentially c-axis-oriented. The scanning electron microscopy results revealed that the grain size of Mn-doped ZnO thin films decreases as the Mn content is increased. None of the Mn metal or its oxide phases can be observed in the Raman spectra of all films. The ultraviolet–visible transmittance and optical band-gap of all films are also examined. In particular, the optical bandgap estimated by the Tauc's plot was found to decrease with an increase of the Mn content. The photoluminescence results revealed that a near-band-edge emission peak centered at about 3.2 eV is dominate for all of the as-deposited films but its intensity decreases dramatically with an increase of the Mn content. In particular, the growth atmosphere has a significant impact on the nucleation process and the optical properties of Mn-doped ZnO thin films, which will be presented and discussed.
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310002031436 博碩士論文區(二樓) 不外借資料 學位論文 TH 008M/0019 423203 4067 2010 一般使用(Normal) 在架 0
310002031444 博碩士論文區(二樓) 不外借資料 學位論文 TH 008M/0019 423203 4067 2010 c.2 一般使用(Normal) 在架 0
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