臺灣博碩士論文加值系統

本研究擬利用射頻磁控式濺鍍系統成長於SrTiO3(1 0 0)基板上La0.8Ba0.2MnO3薄膜。並借用田口品質管理法(Taguchi Methods)來設計實驗，期望可以快速、有系統的方式，找到高居里溫度(TC)、大磁阻(Magnetoresistance ,MR)、低表面均方根粗糙度(RMS)的薄膜成長條件。同時研究La0.8Ba0.2MnO3薄膜一些非常令人感興趣的特性，包括1.薄膜在高溫氧氣氛下的高溫退火效應，2.薄膜受tensile-strain effect對TC的影響，為
何不同於(La1-xCax)MnO3(LCMO)與(La1-xSrx)MnO3(LSMO)薄膜。
吾人成功的以9次實驗及1次確認實驗，就找到La0.8Ba0.2MnO3薄膜特性為相轉變溫為290K左右、磁阻為-20%左右、表面均方根粗糙度為1nm以下的薄膜成長條件。在實驗過程中，發現成長總壓力為70mTorr時，薄膜的粗糙度都在1nm以下。且由減低薄膜厚度來增強tensile-strain effect的影響，使Tp從290K提升至室溫附近。且吾人推論在strain effect影響下，考慮Mn-O-Mn的鍵長及鍵角之改變因素，解釋為何La0.8Ba0.2MnO3薄膜之TC的改變與ＬＣＭＯ和LSMO不同。

The paper of this research is to grow La0.8Ba0.2MnO3 thin films on the SrTiO3 (100) substrate by the radio frequency magnetron sputtering technique .By using of the Taguchi Methods, which is in expected to be fast and systematic method, to design the approaching path for finding growth conditions that exhibit high Curie''s temperature (TC), large Magnetoresistance (MR), and low root mean square roughness (RMS). At the meantime, study some interested characteristics of film, including: 1.The oxygen annealing effect on the physical properties and surface microstructures films: 2. Why the change of TC for film under the tensile-strain is different from (La1-xCax) MnO3
and (La1-xSrx)MnO3 systems.
We succeed in finding best growth conditions with TC, MR and RMS around 290K,-20%, and below 1nm, respectively, in only nine runs and one confirmation experiment. It is found that the films exhibits low roughness
(< 1nm), whenever the total pressure is 70mTorr.The thinner the film, the stronger the tensile-strain effect that Tp raises form 290K to the room temperature. By simplified the cause of TC changed due to the tensile-strain into the length and the angle of Mn-O-Mn bonds, the difference behavior
between LBMO and LCMO and LSMO systems can be understood.

第一章前言………………………………………………….........1
第二章 基本理論…………………………………………………2~20
2-1 磁阻及(La1-xBax)MnO3簡介……………………………...2~6
2-2 雙交換機制(Double exchange mechanism)…….............7~11
2-3 Jahn-Teller distortion……………………………...........12~13
2-4 T.Kanki理論回顧……………………………………...14~16
2-5 田口品質管理法(Taguchi Methods)…………………..17~20
第三章 實驗方法……………………………………………….21~32
3-1 使用Taguchi Methods 製備La0.8Ba0.2MnO3薄膜…...21~29
3-2 實驗儀器設備之簡介…………………...…………….23~32
3-2-1 射頻磁控式濺鍍統……………….........................23
3-2-2 電性及磁阻量測系統………………………...24~26
3-2-3 掃描式探針顯微鏡系統……………………...27~28
3-2-4 雙晶體X光繞射系統………………………..…..29
3-3 薄膜樣品製備及量測方法…………………................30~32
3-3-1 La0.8Ba0.2MnO3薄膜成長步驟…………………...30
3-3-1 La0.8Ba0.2MnO3薄膜特性量測…………….....30~32
第四章 數據分析及討論……………………………................32~55
4-1 田口品質法分析La0.8Ba0.2MnO3……………………...32~40
4-2 La0.8Ba0.2MnO3薄膜oxygen annealing及Strain effect41~46
4-3 La0.8Ba0.2MnO3薄膜X-Ray diffraction分析…………47~55
4-3-1靶材及粉末2θ-ω X-ray diffraction分析…………...47
4-3-2薄膜2θ-ω X-ray diffraction分析……………….48~50
4-3-3薄膜ω-2θ X-ray diffraction 分析………………51~55
第五章 結論…………………………………………………………56
References…………………………………………...…57~58

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[38]吳宗展，中山大學物理所，九十一年碩士論文