10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Low Temperature Plasma Synthesis of Pure and Uniform III-V Semiconductor Nanoparticles from Bulk Metals
NECIP BERKER UNER, Elijah Thimsen, Washington University in St. Louis
Abstract Number: 773 Working Group: Materials Synthesis
Abstract III-V semiconductors constitute a major component of optoelectronic materials. Although the synthesis of many of the III-V materials in nanoparticle form, for example GaAs, InP and InSb, has been well developed, stibnide and nitride particles still do not have an established general route of synthesis. The difficulties in the synthesis of these materials stem from the unavailability of chemically pure precursors or the extremely toxic nature of their chemical precursors, and the very high melting point of nitrides. In this work, aerosols generated from evaporation and condensation of pure bulk metals are utilized as precursors. These aerosols were mixed and then sent into a low temperature plasma (LTP) of argon. It has been recently shown that metal particles vaporize in the LTP despite the low gas temperature, and the generated vapor leads to the formation of monodisperse particles via a process involving nucleation and condensation [1]. Accordingly, the LTP was used to form the III-V compound nanoparticles by vaporization of the feed aerosols, followed by nucleation and condensation. Coagulation is largely prevented due to unipolar negative charging. The process yields nanoparticles which are monodispersed, spherical, crystalline and stoichiometric. This study focuses on the synthesis of Ga-based III-V semiconductor nanoparticles, and results on the synthesis of GaSb and GaN will be reported. Aerosols of pure Ga and pure Sb, and gaseous nitrogen bearing species were used as the precursors. Extensive ex-situ characterization of the produced materials by high resolution transmission electron microscopy, energy dispersive x-ray spectroscopy, electron-energy-loss spectroscopy, x-ray diffraction and inductively-coupled plasma optical emission spectroscopy will be presented. Operation of the aerosol sources will also be discussed.
[1] N. B. Uner and E. Thimsen, “In-Flight Size Focusing of Aerosols by a Low Temperature Plasma,” J. Phys. Chem. C, vol. 121, no. 23, pp. 12936–12944, Jun. 2017.