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Fabrication of highly oriented carbon-nanotube films and its application to an emitter with high efficiency

高取向碳纳米管薄膜的制备及其在高效发射器中的应用

基本信息

批准号：
13650737
负责人：
MATSUMOTO Koichi
金额：
$ 1.98万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650737/
关键词：
carbon nanotube carbon nanotube silicon carbide SiC surface ellipsometry 電界放出気体吸蔵

项目摘要

In order to investigate the initial stage of carbon-nanotube(CNT) formation at the surface decomposition of SiC, we heated the SiC single-crystal substrates (6H-type, C-face polished) in vacuum using an infrared mirror furnace and a turbo-molecular pump, and we analyzed the structure change at the surfaces by means of spectro-ellipsometric measurements.Up to 1100℃, the change in spectra could be interpreted as the decrease of thickness of SiO_2 layer (〜4 nm) on the SiC substrate. At 1150℃ and above, however, spectra were distinctly different from those of the samples heated up to 1100℃, and could be interpreted with a three-phase model, in which the surface layer consists of graphite including X% of voids, where the surface layer thickness t = 10〜50 nm and X = 50〜70%. This indicates that the surface decomposition of SiC is initiated at this temperature and that the spectro-ellipsometric measurements can detect small changes of optical properties of surface due to the initiation of decomposition.When the substrates were heated for a longer time (80〜640 min) at 1300℃, the spectra were essentially different again, and they could be interpreted with a four-phase model, in which the surface layer consists of two graphite layers including different percentages of voids, where the thickness of surface layers t_1 = 20〜50 nm, t_2 = 20〜60 nm and the percentages of voids X = 〜90%, Y = 〜50%. This implied that formation of CNT would start at this temperature. This formation was also detected by FE-SEM observation.

为了研究碳化硅表面分解过程中碳纳米管（CNT）形成的初始阶段，利用红外反射炉和涡轮分子泵在真空中加热碳化硅单晶衬底（6h型，c面抛光），并利用椭偏振光谱测量分析了表面结构的变化。当温度达到1100℃时，光谱的变化可以解释为SiC衬底上SiO_2层厚度的减小（~ 4 nm）。而在1150℃及以上时，光谱与加热至1100℃时的光谱有明显不同，可以用三相模型解释，其中表层由含有X%空隙的石墨组成，其中表层厚度t = 10 ~ 50 nm, X = 50 ~ 70%。这表明SiC的表面分解是在这个温度下开始的，光谱椭偏测量可以检测到由于分解引发的表面光学性质的微小变化。当衬底在1300℃下加热较长时间（80 ~ 640 min）时，光谱又出现了本质上的差异，可以用四相模型来解释，其中表面层由两层石墨层组成，其中表面层厚度t_1 = 20 ~ 50 nm, t_2 = 20 ~ 60 nm，孔隙百分比X = ~ 90%, Y = ~ 50%。这意味着碳纳米管的形成将在这个温度下开始。FE-SEM观察也发现了这种形成。