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.

为了在基板表面照射低电子温度等离子体和自由基，我们通过电感耦合射频氢甲烷等离子体中的孔口将电子温度可控区域与沉积区域分开。对于直径 6 毫米的孔口，我们发现纳米晶金刚石沉积在基材上。进一步地，当甲烷在氢气中的稀释率降低到1％以下时，可以生成相当合格的纳米晶金刚石。相反，当孔口直径增大时，沉积出类金刚石碳膜。这是通过等离子体中 sp3/sp2 烃基比率的降低来解释的。为了将这一特性应用于大面积薄膜沉积，我们采用了中空型磁控管等离子体源。高密度等离子体可以通过静磁场和电场的作用产生。通过降低等离子体源区域中的电子温度，可以降低sp2自由基密度。我们发现具有由正四面体组成的多面体表面的纳米颗粒在低电子温度等离子体中生长。另一方面，在高电子温度等离子体中，沉积由石墨膜制成的纳米墙。这种差异可以通过背景膜中sp2/sp3成分的局部变化来解释。在低电子温度等离子体中，sp3/sp2的比值变大，从而形成像金刚石一样具有sp3结构的纳米颗粒。在低电子温度等离子体中，也可以减少由于高能离子撞击基底而对成核和生长造成的损害，促进反应物在表面的迁移，从而产生具有多面体结构的纳米粒子。低电子温度等离子体对于纳米结构的成核和生长非常有效。