Microplasma synthesis and emergent optoelectronic properties of nanoparticles

Student thesis: Doctoral Thesis

Abstract

Nanoparticles have acquired enormous interest in all application fields of materials science because of the size-dependent material properties, modified in respect to their macroscopic counterparts. These deviations originate from the dominance of surface effects and in the case of 1-10 nanometre particles (i.e. quantum dots) from the confinement of electron wavefunctions in constricting potential wells.
To date, existent synthesis methods viable for industrial integration of quantum dots are limited in obtaining control over particle size, composition, and aggregation at reduced costs. Among all the methods, gas-phase non-equilibrium plasma methods have distinguished themselves for the synthesis of nanoparticles which are not embedded in a matrix or agglomerated. Moreover, nanoparticles of materials which are demanding to synthesize with common chemical and physical routes can be obtained.
Recently, microplasmas have acquired attention for unique qualities of interest to nanomaterial synthesis. These plasmas operate at atmospheric pressure and are confined to a sub-millimetre space. Microplasmas are particularly versatile because of the presence of highly reactive species in the discharge and because they permit to tailor key plasma parameters by the design of reactors. These features enable the synthesis of separated quantum dots from different types of precursors and processing of temperature sensitive materials at reduced costs.
However, while there have been many efforts in recent year for the practical development of reactors and the empirical control of plasma synthesis, little attention has been given to their fundamental physics and the relation between plasma physics and the synthesized nanoparticles. The present work is a modelling and experimental effort that is intended to bridge the two aspects by studying the relation between plasma parameters, nanoparticle formation and the resulting material properties of nanoparticles, with a particular emphasis on their optoelectronic properties and the issues related to their integrability in real world applications.
Date of AwardSep 2020
Original languageEnglish
SupervisorPaul Maguire (Supervisor) & Davide Mariotti (Supervisor)

Keywords

  • Dusty plasmas
  • Atmospheric pressure plasmas
  • Particle heating
  • Silicon Quantum Dot films
  • Nanodiamonds
  • Bismuth Quantum Dots
  • Energy Band Diagrams

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