DocumentCode :
1344636
Title :
Charging, Coagulation, and Heating Model of Nanoparticles in a Low-Pressure Plasma Accounting for Ion–Neutral Collisions
Author :
Galli, Federico ; Kortshagen, Uwe R.
Author_Institution :
Dept. of Mech. Eng., Univ. of Minnesota, Minneapolis, MN, USA
Volume :
38
Issue :
4
fYear :
2010
fDate :
4/1/2010 12:00:00 AM
Firstpage :
803
Lastpage :
809
Abstract :
Low-pressure silane-argon plasmas allow the production of silicon particles of different sizes and morphologies. A better understanding of the correlations between dusty-plasma properties and particle morphology is very important for understanding and optimizing the particle synthesis. An analytical model predicting the nanoparticle charging, coagulation, and heating in a low-pressure plasma is here presented. The model includes the effect of collisions between ions and neutrals in proximity of the particles. In agreement with experimental evidence for pressures of a few torr, a charge distribution that is less negative than the prediction from the collisionless orbital-motion limited theory is obtained. The reduced charging causes an enhanced ion current to the particle while still preventing coagulation and conserving a monodisperse particle size distribution. Ion-electron recombination at the particle surface, together with other particle heating and cooling mechanisms typical of silane-argon plasmas, are studied in a particle-heating model which predicts the nanoparticle temperature. The effect of plasma parameters on the nanoparticle temperature is discussed, and the predictive power of the model is demonstrated from the appearance of photoluminescent properties in silicon nanoparticles, a property present only in crystalline particles. A correlation between plasma power, ion density, particle temperature, and particle crystallinity is finally developed.
Keywords :
cooling; dusty plasmas; nanoparticles; particle size; photoluminescence; plasma density; plasma heating; plasma pressure; plasma temperature; plasma-beam interactions; charge distribution; collisionless orbital-motion; collisions; cooling mechanisms; crystalline particle; dusty plasma; heating model; ion current; ion density; ion-electron recombination; ion-neutral collisions; low-pressure plasma accounting; monodisperse particle size distribution; nanoparticle charging; nanoparticle coagulation; nanoparticle heating; nanoparticle temperature; particle crystallinity; particle surface; particle temperature; photoluminescence; plasma parameters; plasma power; silane-argon plasmas; silicon nanoparticle; Dusty plasma; nanoparticles; particle charging; particle heating; silicon;
fLanguage :
English
Journal_Title :
Plasma Science, IEEE Transactions on
Publisher :
ieee
ISSN :
0093-3813
Type :
jour
DOI :
10.1109/TPS.2009.2035700
Filename :
5342527
Link To Document :
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