氧化鋅奈米針的光催化行為很低。為了改善此狀況，我們研究氧化鋅奈米針長在二氧化鈦膜上所形成的異質接面可以使生命週期增加和增大面積來加強光催化反應。這是因為二氧化鈦的快反應和氧化鋅的大結合能，改善了電子和電洞在價帶和導帶的轉換。
我們更進一步使用液相沉積法將氧化鋅奈米針長在二氧化鈦膜和氮氟共摻雜的二氧化鈦奈米顆粒上，形成異質接面。二氧化鈦膜有便宜、化性穩定、無害和在可見光範圍內不吸收的特性。因此希望藉由氮氟共摻雜來調整二氧化鈦的光吸收邊界，提高對光能量的吸收。
異質接面的優點如下:(1)改善帶電載子的分離(2)增加帶電載子的生命週期(3)增強到吸附基板的接面帶電載子的轉換效率。在此研究中，氧化鋅奈米針長在二氧化鈦膜和氮氟共摻雜的二氧化鈦奈米顆粒上，所形成的異質接面有較高的光催化行為。

Photocatalytic activity of ZnO nanotip is low. To improve this condiction, ZnO nanotip growing on TiO2 film can form heterojunction which make life-time longer and enlarge the area to enhance the photocatalytic activity. This is due to the high reactivity of TiO2 and the large binding energy of ZnO, which improve the process of electron and hole transfer between the corresponding conduction and valence bands.
In conclusion, the heterostructure of ZnO nanotip/TiO2 film and ZnO nanotip/N-F co-doped TiO2 nanoparticle were prepared by aqueous solution deposition (ASD). TiO2 films are inexpensive, chemically stable and harmless, and have no absorption in the visible region. Therefore, N-F co-doped TiO2 nanoparticle is in order to adjust the titanium dioxide the light to absorb the boundary (optical absorption edge), hoping to enhance the absorption of photoenergy.
In this heterojunction configuration, several advantages can be obtained: (1) an improvement of charge separation (2) an increase in the lifetime of the charge carrier (3) an enhancement of the interfacial charge transfer efficiency to adsorbed substrate. In our research, heterojunction of ASD-ZnO nanotip on ASD-TiO2 thin film or ASD-N-F co-doped TiO2 nanoparticle show higher photocatalytic activity.

論文審定書 i
ACKNOWLEDGEMENT ii
摘 要 iii
ABSTRACT iv
CONTENTS v
LIST OF FIGURES viii
LIST OF TABLE x
Chapter 1 1
Introduction 1
1.1 Background of photocatalysis 1
1.2 Photocatalysis 2
1.3 Semiconductor Photocatalysis 2
1.4 Mechanism of Photocatalysis 3
1.5 Properties and applications of TiO2 4
1.6 Properties and applications of ZnO 5
1.7 Preparations of TiO2 6
1.8 Preparations of ZnO 6
1.9 Advantages of aqueous solution dsposition (ASD) 7
1.10 Motivations of Heterojunction 8
Chapter 2 14
Experiments 14
2.1 ASD Deposition System 14
2.2 RF Sputtering 14
2.2 Substrate Cleaning Procedures 15
2.3 ZnO nucleation layer by RF Sputtering and ASD-ZnO nanotip 15
2.3.1 ZnO nucleation layer prepared with ZnO target by RF Sputtering 15
2.3.2 ASD-ZnO nanotip 16
2.4 ASD-TiO2 17
2.4.1 Preparation of (NH4)2TiF6 Solution 17
2.4.2 Preparation of H3BO3 Solution 18
2.4.3 ASD-TiO2 film 18
2.5 Characteristics 19
2.5.1 Physical Property 19
2.5.2 Optical Property 20
2.6 Photocatalytic Activity 20
Chapter 3 27
Results and discussion 27
3.1 Characteristics of ASD-ZnO nanotip/ZnO nucleation layer on XG Corning glass 28
3.1.1 ZnO nucleation layer 28
3.1.2 The length of ASD-ZnO nanotip at different annealing temperature 29
3.1.3 Micro PL of ASD-ZnO nanotip 29
3.1.4 Photocatalytic activity measurement of transmittance of ASD-ZnO nanotip 30
3.2 Characteristics of ASD-TiO2 film on XG Corning glass 30
3.2.1 The thickness of ASD-TiO2 film with different desposition time 30
3.2.2 Photocatalytic activity measurement of transmittance of ASD-TiO2 film 31
3.3 Characteristics of ASD-ZnO nanotip/ZnO nucleation layer/ASD-TiO2 film on XG Corning glass at different annealing temperature 32
3.3.1 ASD-ZnO nanotip/ZnO nucleation layer/ASD-TiO2 film at different annealing temperature 32
3.3.2 Micro PL pattern of ASD-ZnO nanotip on ASD-TiO2 film at the annealing temperatures of 100oC ~ 400oC in N2O for 1 hr 33
3.3.3 Photocatalytic activity measurement of transmittance of ASD-ZnO nanotip on ASD-TiO2 film at the annealing temperatures of 100oC ~ 400oC in N2O for 1 hr 33
3.4 Characteristics of ASD-ZnO nanotip/ZnO nucleation layer/ASD-TiO2 film on XG Corning glass with different desposition time 34
3.4.1 ASD-ZnO nanotip/ZnO nucleation layer/ASD-TiO2 film with different desposition time 34
3.4.2 Micro PL pattern of ASD-ZnO nanotip (3 hrs) on ASD-TiO2 film (1 hr ~ 4 hrs) at the annealing temperatures of 300oC in N2O for 1 hr 35
3.4.3 Photocatalytic activity measurement of tramsmittance of ASD-ZnO nanotip (3 hrs) on ASD-TiO2 film (1 hr ~ 4 hrs) at the annealing temperatures of 300oC in N2O for 1 hr 35
3.5 Characteristics of ASD-ZnO nanotip/ZnO nucleation layer/ASD-N-F co-doped TiO2 nanoparticle on XG Corning glass with different desposition time 36
3.5.1 ASD-ZnO nanotip/ZnO nucleation layer/ASD-N-F co-doped TiO2 nanoparticle with different desposition time 36
3.5.2 Micro PL pattern of ASD-ZnO nanotip (3 hrs) on ASD-N-F co-doped TiO2 nanoparticle (1 hr ~ 4 hrs) at the annealing temperatures of 300oC in N2O for 1 hr 37
3.5.3 Photocatalytic activity measurement of tramsmittance of ASD-ZnO nanotip (3 hrs) on ASD-N-F co-doped TiO2 nanoparticle (1 hr ~ 4 hrs) at the annealing temperatures of 300oC in N2O for 1 hr 37
Chapter 4 58
Conclusions 58
References 59

Chapter 1 Introduction
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Chapter 2 Experiments
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