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Study on High Intensity Field Emission from Carbon Nanotubes Study on High Intensity Field Emission from Carbon Nanotubes Liu, Huarong リュウファロン LIU, Huarrong 総合研究大学院大学博士（工学） Carbon nanotubes (CNT) were firstly discovered by Iijima in 1991. An ideal nanotube can be considered as a hexagonal network of carbon atoms that has been rolled up to make a seamless hollow cylinder. The CNT length ranges from micrometers to centimeters while the diameter is only several nanometers. There are a variety of applications of CNTs since they have many special properties, such as remarkable electronic transport properties,unusual mechanical properties. 　　Among these applications, an important one is to fabricate all kinds of field-emission electron sources. Their huge aspect ratios can dramatically concentrate an applied electric field on their tips; their excellent electric and thermal conductance guarantee good field emission stability; their extremely high melting point makes them possible to work at a critical condition. Therefore, they are considered as promising field emission materials. 　　The purpose of this thesis is focused on producing field emitter with large current density, long lifetime, high stability and good repeatability; the following work has been carried out. 1.Field-emission theory and properties of carbon nanotubes have been reviewed. The 　reason that CNTs are regarded as promising field-emission materials has been 　discussed; the main achievements and demerits of current CNT emitters are also 　investigated. 2.Main equipments related to this research have been introduced, such as experimental 　setup for field-emission test, SEM, and magnetron sputtering deposition system. 3.The rooting technique has been greatly improved by introducing metal substrates 　deposited with thin titanium films. The influence of film thickness on the 　field-emission performance has been studied;2μm is decided as appropriate 　selection. 　More than 15 A/cm2 with a total current of～10mA was reached at～6.0 V/μm. The 　lifetime of this kind of emitter was as long as 800 hours at 5.0 A/cm2 with only a 　2.50% increase of the applied electric field. By introducing Ti-particles during the 　rooting process, the maximum emission current density could reach as high as 　338A/cm2, which was the highest value reported so far. 4.The influence of nano-sized particles appended to CNTs on field emission has been 　investigated; based on the impregnation with RuO2 nano-sized particles and the 　above technique, a low threshold field of ～0.85 V/μm, corresponding to 10 mA/cm2, 　has been reached. 5.Field-emission arrays (FEA) have been introduced to achieve a high emission current. 　The field-emission behavior of a single emitter in a FEA has been studied. A new type 　of FEA is put forward to improve the performance of emitters based on this study; the 　effect has been experimentally proved. At the same time, the reliance of emission 　current density on sample area is also studied. 6.The future work has been discussed; new methods have been put forward, which are 　very possible to further improve the field emission performance for our field emitters. 総研大甲第1092号 thesis 2007-09-28 application/pdf https://ir.soken.ac.jp/record/646/files/甲1092_要旨.pdf https://ir.soken.ac.jp/records/646 eng 修了生論文 | KEK:総合研究大学院大学 http://soken.kek.jp/sokendai/intro/title