Fabrication of Metal Oxides using Atomic Layer Deposition: Towards High- Performance Electronic Devices|RISS 상세보기

다국어 초록 (Multilingual Abstract)

As one of the most popular material classes in electronic devices, metal oxides (MO) is contributing a huge impact to boost future electronics into a new era of big data, and Internet of Thing (IoT). Recent years have witnessed a growing interest in the fabrication of MO materials for integrating electronic circuits. With various applications, the advanced functions of MO in electronic has been actively classified to four fundamental components including electrodes, n- type semiconductor, p-type semiconductor, and dielectric insulator. To develop high-performance electronic devices, this dissertation was organized to assess the potential of diverse functional MO materials towards application for conductive electrodes, n-type semiconductor, and p-type semiconductor. Chapter 1 was oriented for offering the background knowledge of this thesis. Initially, the review of related works to MO materials were provided, followed by the significance of the research topic on advanced electronic devices. Subsequently, the final part of the introduction emphasized thin film transistor (TFT) devices as there are a powerful configuration to evaluate electronic characteristics of MO materials. In chapter 2, a greatly improved electrical conductivity has been achieved by periodically engineering inorganic zinc oxide (ZnO) nanolayer and organic self-assemble monolayer (SAM). The ZnO nanolayer is fabricated in amorphous/crystal phase-composite to employ electronic resonance conducting state for high electron transport. Meanwhile, a thin SAM layer is inserting to prevent enlargement of inorganic crystal domain as well as increase doping concentration. The ZnO/SAM superlattice showed a great opportunity to commercialize as transparent electrodes for emergent solar cel, organic light-emitting diodes, flexible circuit, and see-through electronics. In chapter 3, through an exceptionally high-pressure atomic layer deposition (ALD), a novel amorphous/nanocrystal phase-composite in very thin InOx channel was fabricated, leading to the formation of resonant wave-function for electron transport. Deposition temperature and channel thickness are systematically investigated to regulate carrier concentration as well as phase- composite indium oxide thin film. At low temperature, TFT devices performed enhanced on/off ratio, and high electron mobility corresponding to optimization of evenly distributed crystal domains in amorphous matrix. Beside reported ZnO phase-composite in the prior chapter, this development of InOx phase-composite is an additional experimental observation of the advancement in electronic behavior for next electronic generation. Chapter 4 focused on p-type metal oxide semiconductor fabrication. Specifically, a representative of Tin monoxide (SnO) shows potential due to its unique electronic structure. In this chapter, using atomic layer deposition (ALD) with temperature window, the high-quality SnO with Sn/O composition ratio, close to unity, has successfully fabricated to TFT channel application. The p-type SnO-based TFTs demonstrated acceptable hole mobility range, and on/off current ratio. This achievement holds promise for the development of high-performance p-type oxide. Overall, all tested metal oxides showed interesting electronic properties for conductive, n-type, and p-type semiconductive thin films, these promising materials are attracted great interest in upcoming electronic technologies. The fabrication of hybrid materials employing atomic layer deposition based on their self-limiting surface reactions results in excellent large-scale uniformity, atomic thickness control, and industrial process compatibility. The obtained research outcomes demonstrated the inherent feasibility of applying novel MO material in electronic devices. From these results, this study provides insights into a strategy for tuning MO materials with high- performance properties towards future electronics.

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목차 (Table of Contents)

TABLE OF CONTENTS i
List of Figure. iii
List of Table v
ABSTRACT vi
Chapter 1. Introduction 1

TABLE OF CONTENTS i
List of Figure. iii
List of Table v
ABSTRACT vi
Chapter 1. Introduction 1
1.1. Metal oxides thin film for electronic devices 1
1.2. Atomic layer deposition (ALD) 5
1.3. Band structure of metal oxides 9
1.4. Thin film transistor 22
Chapter 2. Fabrication of Conducting Material of Hybrid Superlattice with Phase-composite Zinc
Oxide (ZnO) and Self-Assemble Monolayer (SAM) 28
2.1. Introduction 29
2.2 Result and Discussion 33
2.3. Conclusion 52
2.4. Experimental Section 53
Chapter 3. Fabrication of N-type Semiconductor of Indium Oxide (InOx) Nanolayer for High-
Performance Thin Film Transistors. 57
3.1. Introduction 58
3.2. Results and Discussion 62
ii
3.3. Conclusion 78
3.4. Experimental section 79
Chapter 4. Fabrication of P-type Semiconductor of Tin Monoxide (SnO) Thin Film using Atomic
Layer Deposition 81
4.1. Introduction 82
4.2. Result and Discussion 85
4.3. Conclusion 98
4.4. Experimental Section 99
Chapter 5. Conclusions 101
5.1. Summary of research 101
5.2. Outlooks and future works 104
Bibliography 105
국문요지. 139
Acknowledgement 142
iii
List of Figure
Figure 1.1.1 Metal oxide applications in electronics 4
Figure 1.2.1 Atomic layer deposition cycle. 8
Figure 1.3.1. Schematic of electronic orbital hybridization for charge transport pathway in the
crystalline and amorphous phase for both conventional Si and metal oxide 10
Figure 1.3.2. Schematic illustration of three different types of carriers in the polymer
semiconductor at different carrier densities ns 16
Figure 1.3.3. Quantum transport simulation using the non-equilibrium Green’s function method
for conventional and phase-composite NC solids 20
Figure 1.4.1. Thin film transistor structures. 24
Figure 1.4.2. Thin film transistor operation. 25
Figure 1.4.3. Typical parameters for electrical characterization of TFT device. 25
Figure 2.2.1. Hybrid superlattice with amorphous/nanocrystalline-phase-composite ZnO
nanolayers and Al-4MP-Al self-assembled monolayers (SAMs). 35
Figure 2.2.2. Hybrid superlattices for flexible transparent conductive films. 39
Figure 2.2.3. Hybrid superlattices with various thickness of constitutional ZnO nanolayer 41
Figure 2.2.4. Electrical stability and flexibility test for samples of Hybrid superlattices and Al:ZnO
thin film 46
Figure 3.2.1: The characteristics of high exposure atomic layer deposition (ALD) for Indium oxide
thin film deposition 64
iv
Figure 3.2.2: Amorphous-nanocrystalline phases of indium oxide characterization by high
resolution transmission electron (HR-TEM) microscopy (TEM). 66
Figure 3.2.3: The electrical properties of Indium oxide thin film transistor (TFT) at different
deposition temperature. 69
Figure 3.2.4. Amorphous/nanocrystalline phase-composite InOx thin films with thickness
variation. 72
Figure 3.2.5. Amorphous/nanocrystalline phase-composite InOx thin film transistor with thickness
variation. 75
Figure 4.1.1. SnO structure 84
Figure 4.2.1. Investigation of reactor for tin mono-oxide atomic layer deposition. 86
Figure 4.2.2. Feature and characteristic of atomic layer deposition SnO thin film 89
Figure 4.2.3. SnO thin-film transistor (TFT) characteristic. 93
Figure 4.2.5. Thickness investigation of SnO TFTs. 97
v
List of Table
Table 2.1: Comparison results for the electrical conductivity of transparent conducting oxides by
different methods 43
Table 2.2. The comparison of TCGDB performance between different thin films. 51
Table 3.1. References listing with comparison of Indium oxide TFTs. 76
Table 4.1. XPS scan of atomic percentages for Sn and O thin film deposited at different reactants.
. 87
Table 4.2. Comparison between the atomic percentages of Sn and O in SnO thin films at different
deposition temperatures. 90

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