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Control of Nucleation and Growth of Nanocrystal Diamond by Irradiation of Radical Low-Temperature Plasma

自由基低温等离子体辐照控制纳米金刚石的成核和生长

基本信息

批准号：
15340195
负责人：
IIZUKA Satoru
金额：
$ 6.08万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

For irradiation of low-electron temperature plasma and radicals on the substrate surface, we separate electron-temperature controllable region from deposition region by orifice in inductively-coupled radio-frequency hydrogen-methane plasma. In case of 6-mm-diamter orifice, we find that nanocrystalline diamond is deposited on the substrate. Further, when the dilution ratio of methane in hydrogen is reduced to be less than 1 %, rather qualified nanocrystalline diamond is created. On the contrary, when the orifice diameter is enlarged, diamond-like carbon film is deposited. It is interpreted by a decrease in the hydrocarbon radical ratio of sp3/sp2 in the plasma. In order to apply this property on wide area film deposition, we employ a hollow-typed magnetron plasma source. A high density plasma can be produced by the effect of static magnetic and electric fields. By reducing the electron-temperature in the plasma source region, the sp2 radical density can de decreased. We find that nanoparticles with polyhedron surfaces composed by regular tetrahedron are grown in the low-electron temperature plasma. On the other hand, in high electron-temperature plasma, nanowalls made of graphite films are deposited. Such difference can be explained by the local change of sp2/sp3 components in the background film. In the low-electron temperature plasma, the ratio of sp3/sp2 becomes large, which results in the formation of nanoparticles with sp3 structure like a diamond. Damage to nucleation and growth due to energetic ions impinging on the substrate can be also reduced in the low-electron temperature plasma, where migration of reactants on the surface is promoted to produce nanoparticles with polyhedron structures.In this way, the control of radicals in low-electron temperature plasma is quite effective for nucleation and growth of nanostructures.

在感应耦合的射频氢-甲烷等离子体中，利用孔板将电子温度可控区与沉积区分开，以辐照低电子温度等离子体和自由基。在孔径为6mm的情况下，我们发现衬底上沉积了纳米晶金刚石。进一步，当甲烷在氢中的稀释比降低到小于1%时，就可以得到比较合格的纳米晶金刚石。相反，当孔直径增大时，会沉积类金刚石碳膜。这可以通过等离子体中sp3/sp2的碳氢自由基比的降低来解释。为了在广域薄膜沉积中应用这一特性，我们采用了一种空心型磁控管等离子体源。静电磁场和电场的作用可产生高密度等离子体。通过降低等离子体源区的电子温度，可以降低sp2自由基密度。我们发现在低温等离子体中生长出了由正四面体组成的多面体表面的纳米颗粒。另一方面，在高电子温度的等离子体中，沉积了由石墨薄膜制成的纳米壁。这种差异可以用背景膜中sp2/sp3组分的局部变化来解释。在低温等离子体中，sp3/sp2的比值变大，形成了类似金刚石的sp3结构的纳米颗粒。在低温等离子体中，由于高能离子撞击衬底而对成核和生长的破坏也可以减少，在低温等离子体中，表面的反应物迁移被促进，产生具有多面体结构的纳米颗粒。这样，低温等离子体中自由基的控制对纳米结构的成核和生长是非常有效的。