A Study on Surface Modification of Polyimide Gate Insulator Based on Solution Process for High Performance OTFT
A Study on Surface Modification of Polyimide Gate Insulator Based on Solution Process for High Performance OTFT
- 주제(키워드) OTFT surface treatment
- 발행기관 고려대학교 대학원
- 지도교수 최동훈
- 발행년도 2018
- 학위수여년월 2018. 8
- 유형 Text
- 학위구분 석사
- 학과 대학원 화학과
- 원문페이지 97 p
- 실제URI http://www.dcollection.net/handler/korea/000000081510
- UCI I804:11009-000000081510
- DOI 10.23186/korea.000000081510.11009.0000815
- 본문언어 영어
- 제출원본 000045953576
초록/요약
ABSTRACT Research on organic tin-film transistors (OTFTs) has progressed because the light weight and flexibility required for next-generation displays can be satisfied. Many studies have examined metal oxide TFTs fabricated using solution processes, as they can potentially be applied in low-cost, large-area electronic devices. However, OTFTs have the disadvantage that the device performance is degraded as compared with that of inorganic TFTs. As the charge mobility is lower than that in inorganic TFTs, it is difficult to apply OTFTs in current displays. Therefore, to increase not only the electrical performance but also the stability in the atmosphere, it is necessary to improve the interface characteristics between the dielectric and the semiconductor. The structure and morphology of organic semiconductors, as well as the movement of charge carriers through the channel, are determined by the interface properties of the dielectric. In addition, as polymer gate-insulating films have fewer functional group than SiO2, further studies are required on the surface modification of such films. First, polyimide was used as an insulator and its surface was modified using alumina, which has a high dielectric constant, as an interlayer thin film. Then a self-assembled monolayer (SAM) of octadecylphosphonic acid (ODPA) was used to block charge trapping and change the surface energy. By improving the charge transfer by the remaining precursor material for forming, the electric characteristics of the OTFTs are improved, consequently, the performance of the device is improved. Second, the effects of physical surface treatments of organic gate-insulating films were investigated. I was able to successfully remove unnecessary ODPA particles by applying a PDMS solution with adhesive properties for the ODPA layer. Therefore, a very smooth ODPA monolayer was obtained on the alumina-treated OGI. Organic semiconductors were well organized and the performance of the device was able to be improved.
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TABLE OF CONTENTS
ABSTRACT I
TABLE OF CONTENTS III
LIST OF SCHEMES VI
LIST OF FIGURES VII
LIST OF TABLES IX
CHAPTER 1: Introduction to Organic Thin Film Transistor
INTRODUCTION 2
1.1. Outline of the Thesis 4
1.2. General Introduction for TFTs 7
1.2.1. Structure of Organic Thin Film Transistors(OTFTs) 7
1.2.2. Operation Principle of OTFTs 11
1.3 Required Characteristics of Organic Gate Insulating Film 14
1.4. Polyimide for Organic Gate Insulator 16
1.5 Oxide Thin Film Transistor with Polyimide Gate Insulator 19
REFERENCES 21
CHAPTER 2: Metal-Oxide Assisted Surface Treatment (MAST) of Polyimide Gate Insulators for High Performance Organic Thin Film Transistors
INTRODUCTION 25
EXPERIMENTAL SECTION 30
2.1. Materials 30
2.2. Polyimide Insulator Polymerization 30
2.3. Metal-Insulator-Metal Device Fabrication 31
2.4. Thin Film Transistors(TFTs) Fabrication 33
2.5.Characteristics and TFT Measurements 33
RESULTS AND DISCUSSION 35
2.6. Polymerization and Properties of Polyimide 35
2.7. Surface Modification Characteristics 35
2.7.1. Surface Energy Measurement and Analysis 35
2.7.2. Atomic Force Microscopy Measurement and Analysis 36
2.8. Polyimide Metal-Insulator-Metal Device Characteristics 40
2.9. Thin Film Transistors(TFTs) Electric Characteristics 43
2.10. The Morphology of 60nm-thick Organic Semiconductor 48
2.11. X-ray diffraction(XRD) Measurement and Analysis 51
CONCLUSION 53
REFERENCES 55
CHAPTER 3: Peeling off Method for Producing Smooths Self-assembled Monolayer on Organic Gate Insulator Interface for High-performance OTFT
INTRODUCTION 60
EXPERIMENTAL SECTION 63
3.1. Materials 63
3.2. Peeling off and Stamping Method Using PDMS 63
3.3. Characterization and Measurements 66
RESULTS AND DISCUSSION 67
3.4. Surface Modification Characteristics 67
3.4.1. Surface Energy Measurement and Analysis 67
3.4.2. Atomic Force Microscopy Measurement and Analysis 69
3.5. Electric Characteristics of Thin Film Transistors(TFTs) 72
3.6. The Morphology and Crystal structure of 60nm-thick Organic Semiconductor 78
3.7. X-ray Diffraction(XRD) Measurement and Analysis 82
CONCLUSION 84
REFERENCES 85
