Plasma Generated Nano Particles

1
Plasma Generated Nano - Particles

• By Maurice Clark
• For Elec 7730
• Fall 2003

2
Outline

• Glossary
• Questions
• Nano Particle Generation
• Thermal Plasma
• Atmospheric Pressure Plasma Discharge
• Radio Frequency Plasma
• Conclusion
• Answers

3
Questions

• What types of plasma can be used to generate
  nanoparticles?
• Name one way that particle size can be controlled
  in thermal plasma.
• What are the advantages of using the DMP reactor?

4
Glossary

• Coagulation-the process by which particles
  collide and adhere to one another to form larger
  particles.
• Agglomerated- clustered together but no coherent.
• HPPD-Hypersonic Plasma Particle Deposition

5
Thermal Plasma
6
Thermal Plasma

• Thermal Plasma Generation
• Gas Discharge Between two Electrodes
• Microwave Frequency
• RF Radio Frequency
• Capacitive
• Inductively
• High Intensity Arc Discharge

Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and
S. A. Campbell, J. Appli Physi Vol 94 (4) pg 2277
2003
7
Thermal Plasma
High Pressure Plasma
Low Pressure Plasma
8
Thermal Plasma

• Conditions
• At or near Atmospheric Pressure
• Temperature of the Ions and Neutrals are almost
  identical to the electron temperature (i.e. they
  are in or close to thermodynamic equilibrium)
• Electron Density of the plasma is very high in
  thermal plasma

9
Thermal Plasma

• DC Thermal Plasma used to generate Al
  Nanoparticles.
• Precursor Gases
• Solid AlCl 3 is heated to 350K
• Argon is main plasma gas with a fraction of
  Hydrogen to ensure the complete conversion of
  chloride vapor reactants to HCl

http//www.me.umn.edu/courses/me8362/Bin_Zhang.pdf
10
Thermal Plasma

• The high temperatures of the plasma gases assist
  in the complete dissociation of reactants into
  their elemental forms.
• Cooler regions, which exist due to the presence
  of steep temperature gradients lead to
  homogeneous particle nucleation
• Homogeneous particle nucleation evolves physical
  condensation of supersaturated vapor.
• Growth of clusters to critical size can occurs
  with or without the presents of ions as
  nucleation sites.

http//www.me.umn.edu/courses/me8362/Bin_Zhang.pdf
11
Thermal Plasma

• Residence Time
• Small residence time leads to the formation of
  smaller nanoparticles.
• Higher residence time leads to the formation of
  larger size nanoparticles.
• Particle growth can be regulated by adjusting
• The input power
• Injection flow rate
• Counter flow gases

http//www.me.umn.edu/courses/me8362/Bin_Zhang.pdf
12
Thermal Plasma

• Synthesis Process
• Metallic particles are nucleated in the plasma
  stream
• A quenching gas which contains a small amount of
  oxygen is used to passivate and quench the growth
  of the nanoparticles.
• Depending on the condition and reactants
  particles may nucleate near downstream nozzle or
  shortly past the nozzle exit.

http//www.me.umn.edu/courses/me8362/Bin_Zhang.pdf

13
HPPD Apparatus

• Setup for depositing a continuous film
• Current 250 A
• Power 10KW
• Main Plasma Gases
• Argon
• Hydrogen
• Gases Reactants for nanoparticles deposition are
  injected up stream.

http//www.me.umn.edu/courses/me8362/Rajesh_Mukher
jee.pdf
14
HPPD Apparatus

• Ar/H2 plasma provides the high heat of reaction
  for the nucleation of nanoparticles from gaseous
  precursors.
• The temperature of the plasma gases reaches about
  5000K
• The thrust produced by the tremendous volume
  expansion helps to completely dissociate Silicon
  tetrachloride and methane
• Helps with subsequent nucleation of silicon
  nanoparticles.
• The carbide is believed go form from the
  dissociation of methane into the silicon
  nanoparticles.

http//www.me.umn.edu/courses/me8362/Rajesh_Mukher
jee.pdf
15
HPPD Apparatus

• Residence for a 20nm particle (between the nozzle
  and substrate) is only about 20us.
• Average velocity is 2000m/s over the 2mm distance
• Average particle size decreases with decreasing
  pressure.

http//www.me.umn.edu/courses/me8362/Rajesh_Mukher
jee.pdf
16
Thermal Plasma
b) SEM Ti/TiC Composite Film
a) SEM micrograph of Silicon Carbide Film
http//www.me.umn.edu/courses/me8362/Rajesh_Mukher
jee.pdf
17
Thermal Plasma
High resolution SEM image Showing nano scale
grain Size same film as below
SEM image of a cross section of SiC film.
Pressure 150 Torr, substrate temp 730 C, SiCl4
flow rate is 67 sccm deposition time was 6 mins
F. Liao, S. Park, J. M. Larson, M. R. Zachariah,
S. L. Girshick, Mater. Lett 57 pg 1982 2003
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R.F. Coupled PlasmaSynthesis of Nano-Particles
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R. F. Inductively Coupled Plasma

• Si nanoparticles formation from pure silane
  plasma and Ar and H dilutions
• 3x10-6 mTorr
• Operating Pressure is between 1-500 mTorr
• RF Field
• A four turn flat spherical coil made of quarter
  inch copper tubes.

Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and
S. A. Campbell, J. Appli Physi Vol 94 (4) pg
2277 2003
20
R. F. Inductively Coupled Plasma

• Three Regimes of Growth
• No observable particles growth
• Low pressure (below 8 mtorr)
• Highly monodispersed particles
• For higher pressures where the plasma on time is
  below a threshold value.
• Polydisperse and agglomerated particles
• Plasma on time exceeds threshold value

Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and
S. A. Campbell,J. Appli Physi Vol 94 (4) pg 2277
2003
21
R. F. Inductively Coupled Plasma

• Pressure 12mtorr and plasma of time of 100s.

b) Pressure of 80mtorr and plasma on time
of 10s.
Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and
S. A. Campbell, J. Appli Physi Vol 94 (4) pg
2277 2003
22
R. F. Inductively Coupled Plasma

• Particle Growth can be controlled by controlling
  the plasma on time.
• Two Phases to Particle growth
• Coagulation
• First 10 sec
• Surface Deposition

Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and
S. A. Campbell, J. Appli Physi Vol 94 (4) pg
2277 2003
23
R. F. Inductively Coupled Plasma

• Electro Statically Trapped Particles (Explain the
  where the mono and polydisperse meet)
• Large Particles are swept out through neutral gas
  or ion drag forces.
• Reduction in the number of particles from the
  plasma, in turn, allows the radical density to
  increase.
• Once the radical density reaches a threshold
  value for nucleation a second generation of
  particles can form through nucleation and
  subsequent coagulation of very small particles.

Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and
S. A. Campbell, J. Appli Physi Vol 94 (4) pg
2277 2003
24
R. F. Inductively Coupled Plasma
Argon/Silane Plasma
-
-
0-15 sec 5nm
Coagulation 15 - 40 sec 5 - 33nm
Coagulation Stops And the Particles Continue to
grow By surface deposition
Z. Shen and U. Kortshagen, J. Vac. Sci. Technol A
20 (1) Jan/Feb 2002
25
Atmospheric Pressure Discharge
26
Atmospheric Pressure Discharge

• Hybrid iron and iron oxide / carbon based
  nanoparticles composites were synthesized.
• Conditions
• 200ml benzene
• 100-300V
• Current 1-3 A
• Angular speed of electrode 1000-3000 rpm
• Plasma gas Ar flow rate is equal to 6 sccm
• Treatment time 6 mins

F. S. Denes, S. Manblache, Y. C. Ma, V.
Shamamian, B.Ravel and S. Prokes, J. Applied
Physics vol 94 (5) 2003
27
Atmospheric Pressure Discharge

• DMP reactor
• Allows the initiation and sustaining of
  discharges in atmospheric pressure environments
  to coexist with the liquid/ vapor mediums.

F. S. Denes, S. Manblache, Y. C. Ma, V.
Shamamian, B.Ravel and S. Prokes, J. Applied
Physics vol 94 (5) 2003
28
Atmospheric Pressure Discharge

• Spirally arranged pin system acts as a source of
  the high current density field emission arc
  source.
• Under DC or AC voltage conditions many micro
  discharges will cover the entire electrode.
• Rotating Electrode
• Spatially homogenizes the multiple micro arcs
• Pumps fresh liquid and vapor into the discharge
  zone
• Thin the boundary lay between the emission tips
  and the rest of the liquid.

F. S. Denes, S. Manblache, Y. C. Ma, V.
Shamamian, B.Ravel and S. Prokes, J. Applied
Physics vol 94 (5) 2003
29
Atmospheric Pressure Discharge

• It is believe that the derivatives are the
  intermediate structures which led to further
  recombination mechanisms to the formation of
  Carbon-based solid state and benzene-insoluble
  nanoparticles systems

F. S. Denes, S. Manblache, Y. C. Ma, V.
Shamamian, B.Ravel and S. Prokes, J. Applied
Physics vol 94 (5) 2003
30
Atmospheric Pressure Discharge
F. S. Denes, S. Manblache, Y. C. Ma, V.
Shamamian, B.Ravel and S. Prokes, J. Applied
Physics vol 94 (5) 2003
31
Conclusion

• A variety of Plasmas can be used to generate
  Nanoparticles

32
References

• http//www.me.umn.edu/courses/me8362/Bin_Zhang.pdf
  
• http//www.me.umn.edu/courses/me8362/Rajesh_Mukher
  jee.pdf
• F. S. Denes, S. Manblache, Y. C. Ma, V.
  Shamamian, B.Ravel and
• S. Prokes, J. Applied Physics vol 94 (5) 2003
• Z. Shen, T. Kim, U. Kortshagen, P.M. McMurry and
  S. A. Campbell, J. Appli Physi Vol 94 (4) pg 2277
  2003
• F. Liao, S. Park, J. M. Larson, M. R. Zachariah,
  S. L. Girshick, Mater. Lett 57 pg 1982 2003
• Z. Shen and U. Kortshagen, J. Vac. Sci. Technol A
  20 (1) Jan/Feb 2002

33
Answers

• Three methods for generating nanoparticles are
  thermal, Atmospheric Pressure Discharge, and R.F
  Plasma.
• Particle size can be controlled in a thermal
  plasma by increasing the flow rate of the
  quenching gas.
• Allows the initiation and sustaining of
  discharges in atmospheric pressure environments
  to coexist with the liquid/ vapor mediums.