Particle trapping, size-filtering, and focusing in the nonthermal plasma synthesis of sub-10 nanometer particles

Zichang Xiong, Steven Lanham, Eric Husmann, Gunnar Nelson, Mohammad Ali Eslamisaray, Jordyn Polito, Yaling Liu, John Goree, Elijah Thimsen, Mark J. Kushner, Uwe R. Kortshagen

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8 Scopus citations


Low-pressure nonthermal flowing plasmas are widely used for the gas-phase synthesis of nanoparticles and quantum dots of materials that are difficult or impractical to synthesize using other techniques. To date, the impact of temporary electrostatic particle trapping in these plasmas has not been recognized, a process that may be leveraged to control particle properties. Here, we present experimental and computational evidence that, during their growth in the plasma, sub-10 nm silicon particles become temporarily confined in an electrostatic trap in radio-frequency excited plasmas until they grow to a size at which the increasing drag force imparted by the flowing gas entrains the particles, carrying them out of the trap. We demonstrate that this trapping enables the size filtering of the synthesized particles, leading to highly monodisperse particle sizes, as well as the electrostatic focusing of the particles onto the reactor centerline. Understanding of the mechanisms and utilization of such particle trapping will enable the design of plasma processes with improved size control and the ability to grow heterostructured nanoparticles.

Original languageEnglish (US)
Article number235202
JournalJournal of Physics D: Applied Physics
Issue number23
StatePublished - Jun 9 2022

Bibliographical note

Funding Information:
This research was supported by the Army Research Office under MURI Grant W911NF-18-1-0240. These results were also based upon work supported by the US Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award Number and DE-SC0020232. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from the US National Science Foundation through the MRSEC (Award Number DMR-2011401) and the NNCI (Award Number ECCS-2025124) programs.

Publisher Copyright:
© 2022 IOP Publishing Ltd.


  • nanoparticle synthesis
  • nonthermal plasma
  • particle trapping
  • size filtering

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