透明導電薄膜現今被許多人所重視，它可運用在許多產業譬如資訊與能源領域等等。其中又以平板顯示器、薄膜太陽能、低散射塗層玻璃運用的多。目前公認最好的透明導電材料為銦錫氧化物(ITO)，但其產量越趨稀少且價格高昂，因此許多替代材料的相關研究越來越盛行。目前發展很好的替代性結構之一，為兩層金屬氧化物(如 ITO, ZnO,TiO2)中間加上一層極薄的金屬層(如 Ag, Cu)，使之大幅提升導電性卻又不減少太多穿透度。若將此結構顛倒過來，在兩層極薄的金屬層中加上一層金屬氧化物，是否也會是一種很好的透明導電薄膜結構？我們期待了解這個結果。

運用光學的基本觀念繼續延伸發展，我們發現這樣的結構因折射率的差異會形成一個共振腔，使入射光在此結構內反覆反射。經過精密計算共振腔的最適厚度，使其當眾多經反覆反射後的光線穿透出來時，能夠形成建設性干涉，增加透明導電玻璃的穿透性；而多加上的一層金屬層亦能提升試片的導電性。本研究前半段即用Ag/ITO/Ag結構計算出ITO的理論最適厚度，再將此結構的試片製備出來，以驗證獲得最佳穿透度的最適厚度。

當Ag層厚度越厚時，試片的電阻雖會變小但光穿透亦會減少。為了使光穿透維持一定的程度，減少Ag層的厚度勢在必行。但當Ag的厚度減少時卻發現Ag薄膜將形成島狀結構，使電子無法在此層銀薄膜順利傳遞。本研究之後半段即在解決此不連續膜結構，使用方法包括：用蒸鍍法製備銀薄膜、用鈦金屬薄膜(Ti)作銀與基板間的緩衝層、用銅金屬薄膜(Cu)作銀與基板間的種晶層，亦採用金屬玻璃薄膜(ZrCu)取代結構中的金屬層。最終發現，使用銅金屬薄膜做為種晶層能使其上的銀金屬薄膜在極薄厚度時，亦能形成連續薄膜，進而在Ag/ITO/Ag透明導電薄膜結構上擁有絕佳的表現，甚至勝過ITO薄膜。

Nowadays, transparent conductive films (TCFs) are more and more important in the world. They are widely used in numbers of electronic devices, including liquid crystal displays, organic light-emitting diodes, touchscreen, and photovoltaics et al. One of the promising structures of TCFs is made of triple-layer which has a thin metal film (e.g., Ag, Cu) between two metallic oxide thin films (e.g., ITO, ZnO, TiO2). These structure gives high conductivity and also transparency. It motivates us to study the TCF with metal/metallic oxide/metal structure with sub-wavelength resonant structure. It is expected that the resonant structure can be used to fine tune the optical transmittance. Fine-tune the parameters of the resonant structure thus can be used to enhance the optical transparency while maintains a high level of electrical conductivity.

According to the fundamental of the optics and getting deepen, the optimal thickness of metal/metallic oxide/metal structure can be calculated by the concept of interference of light. These structure can be seen as resonant cavity which makes the incident light inside reflect persistently by the different refractive index between metal layers and metallic oxide layer. With the optimal thickness, light away from the resonant cavity can form constructive interference which increase the percentage of transmission. Also, the structure have one more metal layer which can increase the electrical conductivity than the former structure. The first half of the study is to calculate the theoretical optimizing thickness with Ag/ITO/Ag structure and then fabricate the sample to testify the result from calculation.

When the Ag layer are thicker, the resistance of the sample certainly be lower, but the transparency will be decreased also. To keep the transmittance in an applicable level, thickness reduction of Ag layer is absolutely needed. However, there comes an island structure when the Ag layer is in an ultra-thin condition, which cannot transmit electron smoothly. The second half of the study is to improve the discontinuous structure condition. The methods include fabricating Ag layer by evaporation system, Inserting ultra-thin Ti or Cu seed layer below Ag layer. Amorphous ZrCu film is also used to substitute Ag layers into the structure. In the result, using Cu seed layer can make the Ag layer above continuous letting the transparent conducting film in Ag/ITO/Ag structure shows the superior behavior even better than single layer ITO thin film.

中文摘要 i
Abstract iii
Table of content v
List of figures viii
List of tables xiv
Chapter 1 Introduction 1
1.1 Transparent conducting films 1
1.2 Discontinuous structure of Ag layer 2
1.3 Motivation 2
Chapter 2 Background and literature review 4
2.1 Haacke’s figure of merit 4
2.2 Transparent conductive films 5
2.2.1 Metal thin films 5
2.2.2 Metallic oxide thin films 6
2.2.3 Metallic glass thin films 7
2.3 Sandwich structure 8
2.2.1 MO/M/MO structure 9
2.2.2 M/MO/M sturerture 9
2.4 Interference of light 10
2.5 Transfer matrix of the film 11
2.6 Refractive index 13
2.7 Spectroscopic ellipsometer 15
2.7.1 Polarized light 16
2.7.2 Structure of spectroscopic ellipsometer 18
2.7.3 Interaction in the surface 19
2.7.4 Del and Psi 20
2.7.5 Data analysis 21
2.7.6 Types of constructed models 23
2.7.7 Application in spectroscopic ellipsometer 24
Chapter 3 Experimental procedures 25
3.1 Substrate preparation 25
3.2 Film preparation 26
3.2.1 Metal thin film 26
3.2.2 Metallic oxide and metallic glass thin film 26
3.3 sample measurement and analysis 27
3.3.1 3D alpha-step profilometer 27
3.3.2 Spectroscopic ellipsometer 28
3.3.3 n & k analyzer 28
3.3.4 Four-point probe 29
3.3.5 Scanning electron microscopy (SEM) 29
3.3.6 Energy dispersive X-ray spectrometer (EDS) 30
3.3.7 X-ray diffractometer (XRD) 30
Chapter 4 Results and discussions 31
4.1 Theoretical optimized thickness 31
4.1.1 Simulation system establishing 31
4.1.2 Complex refractive index acquiring 34
4.1.3 Instrument consistency 36
4.1.4 Optimized thickness of ITO layer 38
4.2 Experimental optimized thickness 39
4.2.1 ITO deposited procedure with and without oxygen 39
4.2.2 Optimized thickness of ITO layer 41
4.2.3 Difference between theoretical and experimental 42
4.3 Discontinuous Ag layer 42
4.4 Improvement for discontinuous Ag ultra-thin film 44
4.4.1 Fabricating Ag layer by e-beam evaporation 44
4.4.2 Substituting ZrCu layer for Ag layer 45
4.4.3 Inserting Ti seed layer below Ag layer 46
4.4.4 Inserting Cu seed layer below Ag layer 48
Chapter 5 Conclusions 50
References 51
Tables 54
Figures 61

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