異質介面由於其邊界條件具有特殊物理性質，引起許多研究討論。層出不窮的新穎材料介面不斷被發現，歸功於原子層等級操控之磊晶技術的發展，使其成為重要議題。基於新穎介面的重要特性，促成了對介面系統的研究動機。樣品在超高真空系統中切斷形成裂截面，再利用剖面式掃描穿隧顯微鏡對介面處進行實驗研究，在這篇論文中，對三個典型異質結構介面直接量測電子結構特性，包含半導體、複合氧化物與超導體系統進行討論。
　　第一個主題為通過高介電材料與三五族半導體的介面，該材料在電晶體發展上遭遇到尺寸微縮的限制，由實驗結果顯示，其介面處存在影響厚度為 0.7nm 的化學鍵結，同時，能帶偏移量在導電帶及價帶均大於 1eV 的能量；第二部分介紹複合氧化物異質結構，由兩絕緣體鋁酸鑭、鈦酸鍶的接合面組成，其介面為大家所熟知的導電介面，利用掃描穿隧顯微鏡可直接量測通過鋁酸鑭與鈦酸鍶介面的能帶影像，並發現介面處存在不尋常的能帶缺口結構。在第三個研究主題，闡述關於通過超導體釔鋇銅氧與鐵磁材料鑭鈣錳氧的電性研究，由電子結構特性通過介面的變化顯示由鄰近效應引起的自旋三重態存在，結果同時顯示超導體與鐵磁材料之間彼此交互影響的同調長度。
　　利用剖面式掃描穿隧顯微鏡研究異質結構為具有特殊技術的量測方法，它提供探索新穎介面結構特殊性質的量測，對於介面基礎性質量測的了解，可提供元件製程改進的重要參考依據。

Hetero-interface has been studied for decades due to the unique physical properties through the interfacial boundary condition. The advance of epitaxial growth technique provides a powerful way to manipulate the interfacial layer in atomic scale accuracy. Consequently, numerous novel hetero-structures are discovered. Motivated by the importance of interesting properties at the novel hetero-interfaces, fundamental mechanisms are elucidated in this study. Utilizing cross-sectional scanning tunneling microscopy (XSTM) with samples cleaved in situ in an ultrahigh vacuum chamber. Topics of the thesis report direct investigations of electronic structures across the interfaces in three model heterostructures, including semiconductors, complex oxides, and superconductor systems.
In the first case across the high-κ/III-V semiconductor interface, the transistor encounters the limitation in size. We demonstrate that the existence of the chemical bonding at the interface is about 0.7nm in thickness. The band offset values are presented to be over 1eV both in conduction and valence band. Secondly, complex oxide heterostructures, the LaAlO3/SrTiO3 is known as a conducting interface between two insulators. The unusual notched structure and the band alignment across the LaAlO3/SrTiO3 interface are directly mapped from STM experiments. In the third case, the detailed investigation of the electronic structures across the interface between the superconductor YBa2Cu3O7-δ and the ferromagnetism La0.7Ca0.3MnO3 is studied. The proximity induced triplet state is demonstrated from the evolution of interfacial electronic properties at the interface. Results also reveal the spatial resolved coherent length between superconductor and ferromagnetism.
The unique technique of using XSTM to study the heterostructures allows us to
explore the interesting properties of novel interfacial structures. The fundamental study across the heterointerfaces potentially provides the crucial point for improving the performance of devices.

中文摘要 i
Abstract iii
Table of Contents vii
List of Figures Captions ix
Chapter 1. Introduction 1
Chapter 2. Experimental instrument and methods 3
2.1 Principles of scanning tunneling microscopy (STM) 3
2.2 Scanning Tunneling spectroscopy (STS) 4
2.3 Cross-sectional scanning tunneling microscopy (X-STM) 6
Chapter 3. Experimental data analysis and the background of theoretical simulation 7
3.1 The tip induced band bending effect (TIBB effect) 7
3.2 Theoretical modeling of tip induced ban bending 10
3.3 Normalized conductance dI/dV 15
Chapter 4. Semiconductor Gd2O3/GaAs (100) hetero-structures [20] 19
4.1 Introduction 19
4.2 Sample preparation of the Gd2O3/GaAs hetero-structures 20
4.3 STM results and discussion 21
4.3.1 Morphology of the Gd2O3/GaAs interface 21
4.3.2 Filled/Empty state STM image of the Gd2O3/GaAs interface 23
4.3.3 Interfacial electronic structures across the Gd2O3/GaAs interface 25
4.3.4 Measured band alignment of the Gd2O3/GaAs interface 26
4.3.5 Calibration of TIBB effect from STS data 27
4.4 Summery 28
Chapter 5. Complex oxide LaAlO3/SrTiO3 hetero-structures [24] 29
5.1 Introduction 29
5.2 Sample preparation of the LaAlO3/SrTiO3 hetero-structures 30
5.3 STM results and discussion 32
5.3.1 Morphology and current image tunneling spectroscopy of the LaAlO3-SrTiO3 interface 32
5.3.2 Interfacial electronic structures across the LaAlO3-SrTiO3 interface 34
5.3.3 Measured band alignment of the LaAlO3-SrTiO3 interface 36
5.3.4 Calibration of TIBB at the LaAlO3-SrTiO3 interface 37
5.4 Summery 39
Chapter 6. Superconductor-ferromagnetism YBa2Cu3O7-δ/La0.7Ca0.3MnO3 hetero- structures 40
6.1 Introduction 40
6.2 Sample preparation of the YBa2Cu3O7-δ/La0.7Ca0.3MnO3 hetero-structures 43
6.3 STM results and discussion 46
6.3.1 Topography and current image tunneling spectroscopy of the YBa2Cu3O7-δ/La0.7Ca0.3MnO3 interface 46
6.3.2 Superconducting gap and pseudogap 48
6.3.3 The Current image tunneling spectroscopy of the YBa2Cu3O7-δ/La0.7Ca0.3MnO3 hetero-structures 50
6.3.4 Evolution of electronic structures across the interface of YBa2Cu3O7-δ/La0.7Ca0.3MnO3 terminated by BaO-MnO2 52
6.3.5 Evolution of electronic structures across the interface of YBa2Cu3O7-δ/La0.7Ca0.3MnO3 terminated by CuO-La0.7Ca0.3O 54
6.3.6 Comparison of proximity induced electronic features at the YBCO/LCMO hetero-interfaces. 56
6.4 Summery 60
Chapter 7. Conclusions 61
Reference 63
List of publications 68

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