Spatiotemporal sampling of growing nanoparticles in an acetylene plasma

Abstract

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.

Step-wise excitation for the determination of the resonance frequency of a microparticle confined in a low pressure plasma

“…ð Þþ z 0 ð10 À3 mÞ; (7) in which D is the arbitrary initial amplitude of the response, x d is the damped angular resonance frequency, s is the decay time constant of the oscillation amplitude, z 0 is the new or post-step probing microparticle's equilibrium position, and / s is the starting phase at t ¼ 0, which is defined as / s ¼ p=2 "falling" ða > 0Þ ðradÞ 3p=2 "rising" ða < 0Þ ðradÞ:…”

“…The first subset includes systems in which particles are grown inside reactive gas-plasmas, such as silane, 4 methane, 5 acetylene, 6,7 and hexamethyldisiloxane. 8 Once grown sufficiently large, these particles may be confined in the positive plasma potential due to the permanent negative charge they obtain from the plasma bulk.…”

Fabrication of ZnO Nanobrushes by H2–C2H2 Plasma Etching for H2 Sensing Applications

“…Dry etching has been performed in a capacitively coupled, asymmetric rf discharge that is sketched in Figure 1 and described in more detail elsewhere. 40 Samples are mounted directly atop the rf electrode as well as placed in the bulk plasma. The working gas pressure in the chamber was measured during processing by a MKS Instruments dual pressure gauge and a MKS Instruments baratron.…”

“…Dry etching has been performed in a capacitively coupled, asymmetric rf discharge that is sketched in Figure and described in more detail elsewhere . Samples are mounted directly atop the rf electrode as well as placed in the bulk plasma.…”

In Situ Laser Light Scattering for Temporally and Locally Resolved Studies on Nanoparticle Trapping in a Gas Aggregation Source

“…Some methods rely on Mie scattering [39][40][41] and others on Rayleigh scattering. [42][43][44][45] Mie scattering techniques are Mie ellipsometry, angular-resolved Mie scattering, and 2D imaging Mie ellipsometry. By these methods, NPs of radii between 80-200 nm can be detected, for example, inside a dusty plasma.…”