Spatiotemporal sampling of growing nanoparticles in an acetylene plasma

摘要

The dynamics of carbonaceous nanoparticle (NP) evolution in its cyclic growth process in a capacitively coupled RF plasma is studied using multiple diagnostic methods. We designed a simple method using biased substrates for spatiotemporal collection of growing NPs at different positions inside the particle cloud and at different time steps during the growth cycle. In addition, self-bias voltage and laser light scattering are in situ measured to monitor the nanoparticle growth. Subsequently, the collected nanoparticles are characterized by scanning electron microscopy (SEM). Correlations between the self-bias voltage and SEM results are presented. We show that different threshold potentials are needed to overcome the confinement of the NPs for collection. This is explained with the spatial and temporal variation of the plasma potential, the NP size, and the ion drag inside the particle cloud. Moreover, the arrangement of the locally collected NPs on the substrate is found to depend on the bias voltage applied to it. Finally, we demonstrate the possibility to control the self-organization and deposition patterns of the nanoparticles by changing the substrate orientation.