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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形成的初始阶段，我们用红外镜面加热炉和涡轮分子泵真空加热了碳化硅单晶衬底(6H型，C面抛光)，并用椭圆偏振光谱仪分析了表面结构的变化。在1100℃范围内，光谱的变化可以解释为碳化硅衬底上SiO_2层(~4 nm)厚度的减少。然而，在1150℃及以上，光谱与加热到1100℃的样品有明显的不同，可以用三相模型来解释，表面层由含有X%孔洞的石墨组成，表面层厚度t=10~50 nm，X=50~70%。当衬底在1300℃下加热较长时间(80~640min)时，光谱又发生了本质上的不同，可以用四相模型来解释，表面层由两层含不同比例空洞的石墨层组成，表面层厚度t1=20~50 nm，t2=20~60 nm，空洞百分比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观察也发现了这一层状结构。