異質結構間的介面能態有機會捕捉電子使得其電子特性受到影響。本工作中，利用理論計算模擬介面能態對於掃描穿隧能譜的影響。經由對有介面能態及無介面能態的考慮，其計算結果可得知在靠近介面的鐵酸鉍表面能帶有不同的彎曲情況。可發現相較於未考慮介面能態之計算結果，考慮介面能態的計算結果較符合實驗上負偏壓的掃描穿隧能譜。在受介面能態的影響下，所計算的穿隧電流貢獻皆來自於導帶。

Trapped electrons at interface states in heterostructures are concerned with the electronic properties. In this work, the effect of interface states on scanning tunneling spectroscopy is simulated by theoretical calculation. Additionally, the surface band bending of BiFeO3 near the interface with and without interface states can be obtained from the computation. At the negative sample bias, the simulated results with the consideration of interface states are more coincident to experiment data. With the influence of interface states, the computation of tunneling current entirely is contributed from the conduction band in heterostructures.

致謝 i
摘要 ii
Abstract iii
目錄 iv
圖目錄 vii
表目錄 xi
第一章緒論 1
1-1 異質結構的簡介 1
1-2 掃描穿隧顯微鏡簡介 4
1-3 理論模擬計算簡介 8
1-3-1 模擬計算簡介 8
1-3-2 模擬結構簡介 10
第二章 研究動機 13
第三章 實驗儀器 14
3-1 儀器介紹 14
3-2 掃描穿隧顯微鏡之穿隧效應原理 15
3-3 掃描穿隧能譜(Scanning tunneling spectroscopy, STS) 17
3-4 掃描穿隧顯微鏡操作模式 19
3-4-1 定電流模式 19
3-4-2 定高度模式 19
3-4-3 電流影像穿隧能譜(Current image tunneling spectroscopy, CITS) 19
3-5 掃描探針製備 21
3-6 超高真空系統 22
3-6-1 真空計 23
3-6-2真空幫浦 24
第四章 理論基礎與流程 25
4-1 探針引致能帶彎曲模型(Tip-induced band bending model) 26
4-2 探針引致能帶彎曲的理論計算 29
4-2-1一維理論模型 29
4-2-2表面能態的影響 31
4-2-3半導體內的電荷密度函數 32
4-3 加入介面能態(Interface state)的參數 33
4-4 理論模擬與分析流程 35
第五章 理論分析與討論 36
5-1 模擬材料的參數-鐵酸鉍(BiFeO3) /鈮摻雜之鈦酸鍶(Nb-doped SrTiO3) 37
5-2 考慮介面能態的理論計算-變動探針與樣品之間的距離 38
5-3 考慮介面能態的理論計算-變動介面能態密度的數量級 40
5-4 分析不含介面能態與含介面能態之理論計算的差異 41
5-4-1 計算結果之電性的比較 41
5-4-2 計算結果之探針(Tip)-真空(Vacuum)-樣品(Sample)能帶圖的比較 43
第六章 結論 45
參考文獻 46
附錄 48

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