RF hollow discharge and its influence on metal nanoclusters Amir - - PowerPoint PPT Presentation

1 4th Graduate Summer Institute “Complex Plasmas” Amir Mohammad Ahadi1, T.Trottenberg2, O.Polonskyi1, T.Strunskus1, H.Kersten2 and F.Faupel1

1 Chair for Multicomponent Materials, CAU-Kiel 2 IEAP, CAU-Kiel

5 August 2014 amah@tf.uni-kiel.de

RF hollow discharge and its influence on metal nanoclusters

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Outline

• Motivation
• Characterization of RF hollow discharge
• Setup
• Single and compensated probe
• Influence of RF Power on discharge
• Effect of pressure
• Influence of reactive admixture
• Nanoclusters in RF hollow discharge
• Effects of nanoclusters on RF plasma
• Influence of discharge on cluster deposition
• Cluster size evolution
• Summary and Outlook

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• RF plasmas are used for plasma polymerization, material

deposition and…

• Clusters: Important role in fabrication of new nanocomposite

materials and in adjusting the properties of nanomaterials.

F.Faupel et.al, Adv.Eng.Mat, Vol.12, No.12, 1177 (2010)

• Due to the symmetric geometry and high ionized discharge,

cylindrical hollow discharge is very interesting tool for study.

Motivation

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Characterization

• f

RF hollow discharge

5 Schematic drawn of experimental setup.

Setup

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Langmuir probe was installed 12 mm far from top ring electrode !

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Single and compensated probe

Langmuir probe:

P=2 Pa, Ar flow= 115 SCCM Power=10 W

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Influence of RF power on discharge

Evolutions of electron temperature and density by loading power

Solid lines are for single probe measurements and dashed lines are for compensated probe measurements.

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V-I probe e measurem rements ents

P=2 Pa Ar flow= 115 SCCM

2 4 6 8 10 12 14 16 18 140 160 180 200 220 240 260 280 300 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4

Discharge Current (A) Discharge Voltage(V) RF Power (W)

2 4 6 8 10 12 14 16 18 114 115 116 117 118 119 120 88.5 88.6 88.7 88.8 88.9 89.0 89.1 89.2 89.3 89.4

Discharge Phase (°) Discharge Impedance (Ohm) RF Power (W)

By increasing the RF power, the plasma gradually becomes more resistive.

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Effect of pressure

• Growing electron density by increasing argon density.
• Decreasing electron temperature due to decreasing mean free path by

pressure.

11 All discharge parameters decreased by increasing the pressure, as the consumed power be constant.

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• Molecular excitation and dissociation are additional source in oxygen

plasma.

K.J.Taylor and G.R. Tynan, J.Vac.Sci.Tech A, 23 (4), 2005

Influence of oxygen admixture

P = 2.00 Pa RF power = 7.00 W

EArgon= 15.8 eV Eoxygen= 12.6 eV

• Higher

ionization energy leads to higher electron temperature .

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Nanoclusters in RF hollow discharge

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Setup

Sample & QCM position

Defe felecto tor With th two slits ts

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Langmuir probe

P=2 Pa Magnetron Power=50 W

Effects of nanoclusters on RF plasma

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 2.8 3.2 3.6 4.0 4.4 4.8 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0

electron Temp (eV) RF Power (w)

With Out cluster With all clusters With neutral clusters

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9

Electron Density (m^-3)*E15 RF Power

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Solid lines are for pure plasma (without clusters) and dashed lines are for plasma in presence of cluster beam.

V-I Probe

2 4 6 8 10 12 14 16 18 140 160 180 200 220 240 260 280 300 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2 4 6 8 10 12 14 16 18 140 160 180 200 220 240 260 280 300

Discharge Current (A) Discharge Voltage (V) RF Power (W)

2 4 6 8 10 12 14 16 18 115 116 117 118 119 120 121 122 88.2 88.3 88.4 88.5 88.6 88.7 88.8 88.9 89.0 89.1 89.2 89.3 89.4 88.2 88.3 88.4 88.5 88.6 88.7 88.8 88.9 89.0 89.1 89.2 89.3 89.4 2 4 6 8 10 12 14 16 18 116 118 120 122

Discharge Phase (°) Discharge Impedance (Ohm) RF Power (W)

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• 10
• 5

5 10 100 200 300 400 500 600 700 800 900

Deposition Rate (a.u.) Distance from center of deposition (mm) RF Power:0 W RF Power:10 W RF Power:2 W

Spatial distribution of deposition rate at different RF powers

Influence of RF Power on cluster beam

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Magnetro tron Power r = 50 W PM.C.= 2 Pa PGAS= = 200 Pa

At higher RF power (higher than 5 w), the nanocluster deposition with and without purification (of neutral clusters) was similar.

19 Cluster er film _ without t RF discharg arge e Cluster er film_ 2 W R RF discharge arge

Cluste ter r size e evoluti tion

• n

DC Power r =100 W PM.C.

C.=2 Pa

PGAS=2 =200 Pa

20 Cluster er film _ 10 W R RF discharge arge

Higher energy enhence cluster charging & more acceleration of nanoparticles the cluster size can grow by coalescence of clusters in the volume.

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Summary

• We could successfully setup and characterize a small RF

discharge at low pressure and low power for material processing.

• At applied conditions, the influence of Ag nanoclusters (were

added to the discharge) on discharge parameters was not noticeable.

• Not only the spatial distribution, but also the deal of

deposited nanoclusters are significantly changed by appling the RF discharge.

• Preliminary evaluations show that the size distribution of

clusters as well as the clusters mean size are affected by the RF discharge.

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Next steps (Outlook)

• Charging of nanoclusters by RF hollow discharge (In progress).
• Using the RF hollow discharge for plasma polymerization.
• Combine with other methods (such as magnetron sputtering
• r GAS ) to produce nanocomposites and also core-shell

nanoparticles. . . .

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• This work has been supported by the German Research

Foundation (DFG) SFB TR 24- B13.

• We would like to thank Stefan Rehders for the technical

construction of the cluster source and hollow cathode and Alexander Hinz for TEM measurements.

Acknowl

• wledg

dgem ements nts

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