Abstract
While well-defined high quality semiconductor nanocrystals have been synthesized successfully in low pressure nonthermal plasmas, moving the field of plasma nanoparticle synthesis to atmospheric pressures is important for lowering its cost and making the process attractive for some industrial applications. Here we present a heating and charging model for silicon nanoparticles during their synthesis in plasmas maintained over a wide range of pressures (10-105 Pa). We consider three collisionality regimes and determine the dominant contribution of each regime to heating and charging of nanoparticles under various plasma conditions. For plasmas maintained at atmospheric pressures we find that the ion current is mainly due to the collisional hydrodynamic contribution. Based on the model, we predict that the formation of nanocrystals at atmospheric pressure requires significantly higher plasma densities than those at low pressures. Strong nanoparticle cooling at atmospheric pressures necessitates high ion densities to reach temperatures required for crystallization of nanoparticles. Using experimentally determined plasma properties from the literature we estimate the nanoparticle temperature that can be achieved during synthesis at atmospheric pressures and predict that temperatures well above those required for crystallization can be achieved. Based on these results we suggest design principles for nanocrystal synthesis at atmospheric pressures.
Original language | English (US) |
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Article number | 035205 |
Journal | Journal of Physics D: Applied Physics |
Volume | 48 |
Issue number | 3 |
DOIs | |
State | Published - Jan 28 2015 |
Bibliographical note
Publisher Copyright:© 2015 IOP Publishing Ltd.
Keywords
- Low-D systems
- Nanoscale science
- Plasma physics