Development of a Synthesis Method for Tailored-Particles using the Coulomb Crystal Formation Process in Reactive Plasmas

利用负电荷粒子在等离子体中的库仑凝固现象，为建立一种合成定制粒子并有效收集它们的方法进行了一系列研究。首先，为了研究颗粒的产生和生长过程，系统地改变了源烃气体、操作压力和射频输入功率。利用微波干涉仪等测量的等离子体参数估算了粒子上的电荷密度和粒子间的作用力，并用自行研制的Mie散射椭圆仪(MSE)监测了捕获粒子的数密度和生长速率。从视频监控中观察到，随机分布的粒子排列成体心立方结构，然后进入紧密堆积的六方晶格结构。基于这些数据，利用估算的库仑耦合参数讨论了凝固条件，MSE分析证明在这种条件下生长的颗粒几乎是完全球形的，尺寸分散性很小，这与扫描电子显微镜的观察结果是一致的。研究了合成层状结构裁剪粒子的方法，如将源气从甲烷转换为硅烷，以及层状结构粒子MSR数据的理论公式的方法。

A series of study for establishing a method to synthesize tailored particles and collect them efficiently has been carried out by utilizing the phenomenon of Coulomb solidification of negatively charged particles in a plasma. Firstly, for the study of the production and growth processes of particles, the source hydrocarbon gases, the operating pressure, and the RF input power have been systematically changed. The charged density on a particle and the force between the particles have been estimated from the measured plasma parameters by microwave interferometer etc. The number density and the growth rate of trapped particles have also been monitored by the Mie-scattering ellipsometry (MSE) technique which has been developed by ourselves. From the video monitoring, the alignment of randomly distributed particles into a body centered cubic structure, and then into a closely packed hexagonal lattice structure has been observed. Based on these data the solidification condition has been argued using the estimated Coulomb coupling parameter.The particles grown under such a condition have been proved to be almost perfectly spherical and the size dispersion is very small by the MSE analysis, which is consistent with the SEM observation. The synthesis of tailored particles with layred structure is being studied e.g.by switching the source gas from methane to silane as well as the method of the theoretical formulation of the MSR data for particles with the layred structure.