系統識別號 U0026-0608202014472600
論文名稱(中文) 超薄鈦酸鍶獨立薄膜的室溫鐵電特性
論文名稱(英文) Room-temperature ferroelectricity in ultrathin freestanding SrTiO3 thin film
校院名稱 成功大學
系所名稱(中) 物理學系
系所名稱(英) Department of Physics
學年度 108
學期 2
出版年 109
研究生(中文) 邱濬謙
研究生(英文) Chun-Chien Chiu
學號 L26071142
學位類別 碩士
語文別 中文
論文頁數 52頁
口試委員 指導教授-楊展其
中文關鍵字 獨立自支撐  鐵電性  鈦酸鍶 
英文關鍵字 freestanding  ferroelectric  SrTiO3 
中文摘要 二維材料作為現今熱門研究之一,其中不僅僅是因為其在應用面上有拓展矽半導體製程的可能性,在研究面上當材料縮小到一定尺度,電子將會被侷限而常常導致磁性或電子結構之間會以特別的形式交互影響,而在相異的材料系統中體現豐富的物理特性。其中Freestanding (FS) 技術這項技術已被廣泛的運用在包括微電機系統(MEMs)1,2、sensors3,4等相關應用之中。在科學研究上不僅為整合不同系統材料提供很大的潛力,對於材料應用的開發上,更可以增加調控的自由度。我們在本實驗研究中發現,利用FS 轉移後超薄的鈦酸鍶(SrTiO3, STO)薄膜,可檢驗出顯著的鐵電特性,經過X光繞射的晶格結構鑑定後發現,樣品轉移過後仍然保持tetragonal結構,以及在X光線性二色性吸收光譜(X-ray Linear Dichroism)中確認了原本位於晶格中心的Ti原子偏離了中心位置,結構的不對稱引發出鐵電特性。這個結果不僅提供了一種製備室溫鐵電鈦酸鍶薄膜的方法,還在鐵電性材料中增添了新的選擇,並且在低維度中仍保有鐵電特性,對於鐵電薄膜的應用上,多了更多的可能性,拓展新穎量子材料發展的新思路。
英文摘要 Free-standing (FS) techniques have been adopted in a wide spectrum of applications, including Microelectromechanical Systems (MEMs) , catalysis, sensors, tissue engineering and so on. In academic studies, this technique provides great degrees of freedom and potential for the integration of different material systems. This offers more possibilities for the development of materials.
In this work, we revealed the significant room-temperature ferroelectricity in freestanding strontium titanate (SrTiO3, STO) ultrathin films. The ferroelectric property was verified via conducting Kelvin probe force microscopy (cKPFM), while the lattice exhibits a structure transition from cubic to tetragonal, carried out by reciprocal space mapping. The spatial symmetry breaking of STO lattice is originated from Sr vacancy and polar nanoregion. It leads to the switchable polarity in ultrathin STO thin films. Our results not only provide a promising option served as a candidate of ferroelectric materials but also pave a new way for the development of material integration engineering.
論文目次 總目錄
摘要 I
Abstract II
圖目錄 XII
第1章. 緒論 1
第2章. 文獻回顧 2
2.1. Freestanding 簡介 2
2.2. 鐵電材料簡介 4
2.3. SrTiO3介紹 8
2.4. 奈米極化區域 (Polar Nanoregion, PNR)介紹 10
第3章. 實驗原理與方法 12
3.1. 脈衝雷射沉積系統 12
3.2. 掃描式探針顯微術 16
3.3. 壓電力顯微鏡 (Piezoelectric Force Microscopy, PFM) 18
3.4. 接觸式表面電位顯微鏡 (contact Kelvin Probe Force Microscopy, cKPFM) 21
3.5. P-E 曲線量測 24
3.6. X光繞射 (X-ray Diffraction, XRD) 25
3.7. X射線吸收光譜 (X-ray absorption spectroscopy) 28
3.7.1. 元素選擇性(Element selectivity) 31
3.7.2. 價態敏感性 (Valence state sensitivity) 32
3.7.3. 自旋態敏感性 (Spin state sensitivity) 33
3.7.4. 對局部配位敏感 (Sensitivity to the local coordination) 34
3.8. 偏振相關 (Polarization dependence) 35
3.8.1. 磁性圓二色性 (Magnetic circular dichroism, MCD) 35
3.8.2. 晶體場線性二向性 (Crystal field linear dichroism) 36
3.8.3. 磁性線性二向性 (Magnetic linear dichroism) 38
第4章. 實驗結果與討論 39
4.1. SrTiO3的鐵電特性 39
4.2. Freestanding-STO結構分析 44
4.3. XAS結果分析 46
第5章. 結論 49
參考文獻 50

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