Solution-based processing of 1D van der waals materials for scalable fabrication of electronic devices

국문 초록 (Abstract)

전자소자의 고집적화가 진행됨에 따라 나노미터 이하 스케일에서 전자 특성의 열화가 없고 구조적으로 안정한 소재에 대한 수요가 증가하고 있다. 이러한 요구를 충족시키기 위해 그래핀의 발견 이후 2차원 소재에 대한 연구가 활발히 진행되어왔으며, 2차원 소재의 합성법, 원자 수준의 박리법, 그리고 그에 따른 전자 특성에 대한 다양한 연구가 이루어졌다. 최근 이러한 연구 흐름은 2차원 소재보다 한 차원 낮은 1차원 물질로 확장되었으며, 현재 1차원 소재는 많은 관심을 받으며 활발히 연구되고 있다. 그러나 기존 2차원 소재에 비해 1차원 물질은 물질의 종류, 합성법, 박리법, 전자 특성 등에서 아직 밝혀져야 할 부분이 많다.
본 연구에서는 1차원 반데르발스 물질의 구조와 합성법을 비롯해 탑다운 방식을 기반으로 한 액상박리법에 대해 다루었다. 특히, 액상박리 시 소재의 용매 내 분산 경향을 해석하는 방법과 박리 용매를 최적화하는 방법을 제시하였다. 이를 바탕으로, 액상박리된 1차원 반데르발스 소재를 대면적 구조를 포함하는 대표적인 세 가지 구조로 구분하여 소자를 제작하고, 소자의 구조에 따른 전계효과 트랜지스터(FET) 및 센서 소자 특성을 비교 분석하였다. 이러한 연구는 1차원소재의 활용 가능성을 확장하고, 전자 및 센서 응용 분야에서의 새로운 방향성을 제시한다.

다국어 초록 (Multilingual Abstract)

As the integration of electronic devices continues to advance, there is an increasing demand for materials that maintain stable electronic properties and structural integrity at scales below the nanometer range. To meet these demands, research on two-dimensional (2D) materials has flourished following the discovery of graphene, with significant progress in synthesis methods, exfoliation techniques at the atomic level, and the resulting electronic properties. This research trend has shifted towards materials with one-dimensional (1D) structures, which are receiving growing attention. However, compared to 2D materials, 1D materials still face many unknowns regarding material diversity, synthesis methods, exfoliation techniques, and electronic properties.
This study focuses on the structure and synthesis methods of 1D van der Waals (vdW) materials, as well as liquid-phase exfoliation (LPE) based on the top-down approach. It also presents methods for analyzing the dispersion behavior of these materials in solvents and optimizing exfoliation solvents. The exfoliated 1D vdW materials were divided into three representative structural categories, and the characteristics of their field-effect transistors (FETs) and sensor devices were compared based on their structures. This research aims to broaden the potential applications of 1D materials and provide new insights for electronic and sensor technologies.

목차 (Table of Contents)

• Chapter 1. Introduction 1
• 1.1. Preface 1
• 1.2. Structural features of 1D van der Waals materials 3
• 1.3. Liquid phase exfoliation of 1D van der Waals materials 5
• 1.4. Proposed device structures for various channel dimensions 7
• 1.5. References 11
• Chapter 2. Synthesis of 1D van der Waals Materials 12
• 2.1. Solid-state reaction 12
• 2.1.1 Introduction 12
• 2.1.2 Experimental method 14
• 2.1.3 Results and Discussion 15
• 2.1.4 Conclusion 27
• 2.1.5 References 28
• 2.2. Chemical vapor transport (CVT) method 33
• 2.2.1 Introduction 33
• 2.2.2 Experimental method 35
• 2.2.3 Results and Discussion 37
• 2.2.4 Conclusion 52
• 2.2.5 References 52
• 2.3 Hydrothermal reaction 55
• 2.3.1 Introduction 55
• 2.3.2 Experimental method 56
• 2.3.3 Results and Discussion 57
• 2.3.4 Conclusion 65
• 2.3.5 References 65
• Chapter 3. Liquid Phase Exfoliation of 1D van der Waals Materials 68
• 3.1. Single solvent exfoliation 68
• 3.1.1 Introduction 68
• 3.1.2 Experimental method 71
• 3.1.3 Results and Discussion 73
• 3.1.4 Conclusion 90
• 3.1.5 References 90
• 3.2. Co-solvent exfoliation 93
• 3.2.1 Introduction 93
• 3.2.2 Experimental method 94
• 3.2.3 Results and Discussion 95
• 3.2.4 Conclusion 106
• 3.2.5 References 106
• 3.3. High polar solvent exfoliation 108
• 3.3.1 Introduction 108
• 3.3.2 Experimental method 109
• 3.3.3 Results and Discussion 111
• 3.3.4 Conclusion 125
• 3.3.5 References 125
• Chapter 4. Formation of device structures and electronic properties 127
• 4.1. Single nanowire structure 127
• 4.1.1 Introduction 127
• 4.1.2 Experimental method 128
• 4.1.3 Results and Discussion 130
• 4.1.4 Conclusion 147
• 4.1.5 References 147
• 4.2. Nanowire network structure: Solution blade coating method 149
• 4.2.1 Introduction 149
• 4.2.2 Experimental method 151
• 4.2.3 Results and Discussion 153
• 4.2.4 Conclusion 164
• 4.2.5 References 165
• 4.3. Nanowire network structure: Solution spin coating method 167
• 4.3.1 Introduction 167
• 4.3.2 Experimental method 169
• 4.3.3 Results and Discussion 172
• 4.3.4 Conclusion 196
• 4.3.5 References 196
• 4.4. Hybrid dual channel structure: Solution blade coating and DC sputtering 200
• 4.4.1 Introduction 200
• 4.4.2 Experimental method 201
• 4.4.3 Results and Discussion 204
• 4.4.4 Conclusion 226
• 4.4.5 References 226
• 4.5 Nanowire thin-film structure: Vacuum filtration process 227
• 4.5.1 Introduction 227
• 4.5.2 Experimental method 228
• 4.5.3 Results and Discussion 230
• 4.5.4 Conclusion 254
• 4.5.5 References 255