Fabrication of patterned carbon nanotube field emission cathodes for lighting source
- 주제(키워드) carbon nanotube , field emission , RNA-CNT hybrids , CNT emitter
- 발행기관 고려대학교 대학원
- 지도교수 박정호
- 발행년도 2010
- 학위수여년월 2010. 2
- 학위구분 박사
- 학과 일반대학원 전자컴퓨터공학과
- 세부전공 마이크로시스템 및 반도체 전공
- 원문페이지 152 p
- 실제URI http://www.dcollection.net/handler/korea/000000021671
- 본문언어 영어
- 제출원본 000045590025
초록/요약
Carbon nanotubes (CNTs) have high aspect ratio, small radius of curvature, high electrical and thermal conductivity, high mechanical strength, high chemical stability and low work function, thus, they have emerged as the most promising field emitter materials for application in field emission lighting source. In order to fabricate CNT based field emission lighting source, several approaches were proposed during the last decade but low yield of CNT emitters, weak bonding between CNTs and various substrates, dispersion of CNTs and micro-patterning are the key technological issues still to be solved. In this thesis, the patterned cathodes were fabricated by combining three different methods (screen printing, electrophoresis, and spraying) with photolithography, respectively. In addition, a novel metal mesh as gate electrode for CNT based triode structure was suggested. For screen printing method, the photosensitive CNT paste was prepared by a 3-roll milling process of the mixture having multi walled CNTs, organic binder, terpineol, and additives such as inorganic binder and photosensitive polymer, and acetone utilized as the developer. The patterns were well-defined and the organic vehicle in the patterns was partially removed. The CNT patterns without a firing showed a high current density of 1.35 mA/cm2 at 3.25 V/um and low turn-on field of 2.2 V/um at 100 mA/cm2. Acetone as developer can not only form CNT pattern but also effectively remove the organic vehicles in the printed CNT film from the photosensitive paste with aryl resin. The well-dispersed ribonucleic acid (RNA)-CNT aqueous solution as a black suspension for the electrophoretic and spray methods was suggested. The CNTs were effectively dispersed and functionalized by being wrapped with RNA. The adhesion of RNA-CNT hybrids on the ITO glass substrate is stronger than that of CNT paste on the ITO glass substrate. In order to achieve a selective deposition, electrophoretic and spray methods using the RNA-CNT suspension can be used the pre-patterned substrate by common positive or negative tone photoresists. Thus, the CNT patterns were well-defined on ITO glass substrate or metal/ITO glass substrate by the two methods. As a result, the cathodes with the well-defined patterns showed a uniform emission sites across the entire surface and also exhibited a high current density (approximately ≤15 mA/cm2). The RNA-CNT hybrids compared favorably to other factionalized CNTs for use in the electrophoretic and spray method. A CNT-based triode structure consisting of a metal mesh with a spacer as a gate, the pattered CNT cathode, and anode was fabricated. The metal mesh was designed with trenches and numerous holes to make a gap between gate and cathode electrodes and to provide electrons with a highly efficient passage. We observed that this metal mesh decreased the vibration and leakage current owing to high electric field generated from anode. As a result, the uniformity and stability of this field emission lamp was improved.
more목차
CHAPTER 1 Introduction 1
CHAPTER 2 Research Background 6
2.1 . Field Emission Theory 6
2.2 . Carbon Nanotubes 11
2.2.1 . Carbon Nanotube Structure 11
2.2.2 . Properties of Carbon Nanotube 19
2.2.3 . Functionalization and Dispersion of Carbon Nanotube 24
2.2.4 . Hybridization and Dispersion by Nucleic Acid 26
2.2.5 . Field Emission from Carbon Nanotube Film 34
2.3 . Fabrication Methods of Carbon Nanotube Patterns 44
2.3.1 . Direct Growth on Catalyst Patterns 44
2.3.2 . Screen Printing Method 48
2.3.3 . Electrophoretic Deposition 51
2.3.4 . Spray Method 59
CHAPTER 3 Carbon Nanotube Pattern/Array Formation 61
3.1 . CNT Pattern Formation using Photosensitive Paste 61
3.2 . Pattern Formation using CNT Suspension 73
3.2.1 . Preparation and Analysis of RNA-CNT Aqueous Solution 73
3.2.2 . CNT Pattern Formation by Electrophretic Deposition 87
3.2.3 . CNT Pattern Formation by Spray Method 103
CHAPTER 4 Triode-Type Field Emission Lamp using a Novel Metal Mesh 110
4.1 . Fabrication of Triode Structure using a Metal Mesh 110
4.2 . Field Emission Properties of the Triode-Type Lamp 114
CHAPTER 5 Conclusions 119
REFERENCE 123
