Plasma Sources and Applications Centre, NIE and Institute of Advanced Studies, Nanyang Technological University, 1 Nanyang Walk, 637616, Singapore.
Nanoscale. 2011 Feb;3(2):731-40. doi: 10.1039/c0nr00718h. Epub 2010 Nov 16.
Through a combinatorial approach involving experimental measurement and plasma modelling, it is shown that a high degree of control over diamond-like nanocarbon film sp3/sp2 ratio (and hence film properties) may be exercised, starting at the level of electrons (through modification of the plasma electron energy distribution function). Hydrogenated amorphous carbon nanoparticle films with high percentages of diamond-like bonds are grown using a middle-frequency (2 MHz) inductively coupled Ar+CH4 plasma. The sp3 fractions measured by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy in the thin films are explained qualitatively using sp3/sp2 ratios 1) derived from calculated sp3 and sp2 hybridized precursor species densities in a global plasma discharge model and 2) measured experimentally. It is shown that at high discharge power and lower CH4 concentrations, the sp3/sp2 fraction is higher. Our results suggest that a combination of predictive modeling and experimental studies is instrumental to achieve deterministically grown made-to-order diamond-like nanocarbons suitable for a variety of applications spanning from nano-magnetic resonance imaging to spin-flip quantum information devices. This deterministic approach can be extended to graphene, carbon nanotips, nanodiamond and other nanocarbon materials for a variety of applications.
通过组合实验测量和等离子体建模的方法，从电子层面（通过改变等离子体电子能量分布函数）出发，研究表明可以实现对类金刚石纳米碳薄膜 sp3/sp2 比（进而对薄膜性能）的高度控制。采用中频（2 MHz）感应耦合 Ar+CH4 等离子体，生长出具有高比例类金刚石键的氢化非晶碳纳米颗粒薄膜。使用 X 射线光电子能谱（XPS）和拉曼光谱在薄膜中测量的 sp3 分数，通过使用 1）源自全局等离子体放电模型中计算出的 sp3 和 sp2 杂化前体物质密度的 sp3/sp2 比以及 2）通过实验测量得出的 sp3/sp2 比来定性解释。结果表明，在高放电功率和低 CH4 浓度下，sp3/sp2 分数更高。我们的结果表明，预测建模和实验研究的结合对于实现确定性生长的定制类金刚石纳米碳是至关重要的，这些纳米碳适用于从纳米磁共振成像到自旋翻转量子信息器件等各种应用。这种确定性方法可以扩展到石墨烯、碳纳米尖端、纳米金刚石和其他纳米碳材料，以满足各种应用的需求。
