氧化鋅由於具備獨特的光、電、磁以及壓電特性並且具有廣泛的應用性，因此是所有半導體材料中備受矚目的材料之一，因而在近幾年吸引了相當廣泛的研究。由於不同型態、維度及尺寸的氧化鋅具有其不同的性質及應用面，所以如何設計及控制氧化鋅奈米結構的成長便成了研究學者們的重點。
在本研究中，我們專注於通過擴散銅使氧化鋅奈米線會從n型轉化成p型。對於製作P型氧化鋅，以銅作為摻雜物。通過擴散的形式使銅均勻摻雜到氧化鋅奈米線中。因為其價電子數目比鋅原子的價電子數量少，等效上會帶來一個的空位，這個多出的空位即可視為電洞，從而轉化成p型材料。當中設計了兩種方法來實現材料的轉化，第一種是擴散源是銅薄膜，第二種為銅奈米顆粒。發現擴散的驅動力會受溫度和擴散源的多寡而影響其擴散行為。SEM、XRE、TEM和XPS會協助分析氧化鋅奈米線在實驗中的變化。
其實驗結果將為優化氧化鋅奈米線的電性提供一個良好的起點。我們也會利用電性量測的結果，去判斷氧化鋅奈米線是否因為銅的摻雜而從n型材料轉化成p型材料。

ZnO is one of the most important materials that has attracted much attention due to its unique optical, electrical, magnetic and piezoelectric properties as well as versatile applications. In the present research, we focus on modifying ZnO nanowires from n-type to p-type with Cu diffusion. For the fabrication of p-type ZnO nanowires, attempts were made to dope Cu uniformly into the ZnO nanowire by diffusion. It was based on the understanding that when Cu replaces zinc, a hole will be formed (one less electron), thus forming a p-type semiconductor. There are two methods designed to realize the transformation. For method 1, the source is Cu metal film. For method 2, Cu particles are used as the diffusion source. It was found that the driving force of diffusion is influenced by temperature and source amount. SEM, XRD, TEM and XPS were used to characterize the pristine and treated ZnO nanowires. Using electrical properties measurement, we can confirm that ZnO nanowire was transited from n-type to p-type by Cu. The result shall provide a good starting point for optimizing electrical properties of ZnO nanowires.

摘 要 i
Abstract ii
致 謝 iii
Acknowledgement iv
Contents 1
Chapter 1 Introduction 5
1.1 Nanotechnology 5
1.1.1 One-dimensional Materials 6
1.2 ZnO Nanowires 7
1.2.1 Properties of ZnO 7
1.2.2 Vapor-liquid-solid (VLS) Growth Mechanism 9
1.2.3 The Application of ZnO Nanowires 11
1.3 The Doping and Formation of p-type ZnO by Cu 13
1.4 In-situ TEM observation 15
1.4.1 In-situ TEM of the Nanowire Growth 15
1.4.2 In-situ TEM for heating process 17
1.5 The Principle of Diffusion 19
1.6 Motivation 21
Chapter 2 Experimental Section 22
2.1 Experimental Flowchart 22
2.2 Experimental Procedures 23
2.2.1 Synthesis of ZnO Nanowires 23
2.2.2 The Preparation of Silicon Substrate for the Growth ZnO Nanowires... 23
2.2.3 The Growth of ZnO Nanowires in Three Zone Furnace 23
2.2.4 The Preparation of Heating Chip for ZnO Nanowires and Cu Source……… 25
2.2.5 Heating Experiment with In-situ TEM 28
2.2.6 The Preparation of the Samples for XPS Analysis 29
2.2.7 Electrical Properties Measurement of ZnO Nanowires 29
2.3 Experimental Equipments 31
2.3.1 Three Zone Furnace 31
2.3.2 Optical Microscope (OM) 32
2.3.3 Scanning Electron Microscope (SEM) 33
2.3.4 X-Ray Diffractometer (XRD) 34
2.3.5 Transmission Electron Microscope (TEM) 35
2.3.6 The Heating Holder of In-situ TEM 37
2.3.7 Energy-Dispersive X-Ray Spectroscopy (EDS) 38
2.3.8 X-ray Photoelectron Spectroscopy (XPS) 39
2.3.9 Electrical Properties Measurement System 40
Chapter 3 Results and Discussion 41
3.1 Analysis of Characteristics for ZnO Nanowires 41
3.1.1 The Structure of ZnO Nanowires 41
3.2 Preparation of Patterned Chip with ZnO Nanowires in Contact with Cu Source 43
3.2.1 In-site TEM Investigation of Solid-state Diffusion Reaction upon Heating 44
3.2.2 The Analysis of Reaction Interface 48
3.2.3 Thermodynamic Analysis of Reactions 49
3.3 XPS Analysis 52
3.4 The Analysis of Heating Chip (at 600 °C for 1 hour) 54
3.5 Electrical Properties Measurement 57
3.6 Diffusion and Formation of p-type ZnO 61
3.7 Durability Test of p-type ZnO Nanowire 63
Chapter 4 Summary and Conclusions 64
Chapter 5 Future Prospects 66
References 68

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