FB100 Plasma Chemical
Processes
Mgr. Ondřej Jašek, Ph.D.
jasek@physics.muni.cz
Fullerene synthesis
2
Laser ablation of graphite
target in He atmosphere
pressure ~ 100 Torr (13
kPa)
Separation in centrifuge
and liquid chromatography
Fast detection by color in
fullerene/toluene
suspension C60 – wine red,
C70 brown.
Arc discharge
He atmosphere, 13 kPa,
Arc discharge electric parameters:
~100 A, 24V.
Deposit collected on reactors cooled
reactor walls
Analysis – mass spectrometry
C60-720 amu, C70 – 840 amu.
NMR C60 1 line, C70 5 lines - symmetries.
Lawrence T. Scott, Methods for the Chemical Synthesis of Fullerenes, Angew. Chem. Int. Ed. 2004,
43, 4994 – 5007.
Fullerene synthesis
J.-F. Bilodeauyx, T. Alexakisyz, J.-L. Meuniery and P. G. Tzantrizosz, Model of the
synthesis of fullerenes by the plasma torch dissociation of C2Cl4, J. Phys. D: Appl.
Phys. 30 (1997) 2403–2410.
4
Stainless steele water cooled reactor 20 cm diameter
25 cm height
Precursors toluene, benzene, CCl4 (0,2 – 0,3 cm3/min)
RF power - 27 MHz,2 kW, dep. time 10 -30 minut
Helium atmosphere 60 – 150 Torr
Fullerene synthesis by decompostion of CCl4 in
rf dicharge in helium atmosphere
Growth of diamond layers – ultrananocrystalline diamond
5
Nucleation of ultra-nanocrystalline diamond
6
Bias Enhanced Nucleation – BEN in-situ nucleation density ~ 1012 cm2
Ultra-nanocrystalline diamond
7
High concentration of CH4 – 10 % against 1-2 % traditionally used, 2x lower layer roughness
H/N/C mixtures – T. Frgala, PhD Thesis
Preferential growth of <100> orientation
Nucleation of ultra-nanocrystalline diamond
Astex type reactor MW power 2500 W, pressure 50 mbar, and process time 1 h. Si substrate (10 x
10 mm) is 1-2 cm from plasma ball and is heated by plasma to 750 C.
The diamond can also be nucleated from CO2/H2 mixture in the remote mw plasma reactor. The
nucleation density is higher and sp2 content lower but time of nucleation is 15 hours. At high CO2
concentrations (40 %) the diamond seeds are etched away.
Tibor Izak, Alexey Sveshnikov, Pavel Demo, and Alexander Kromka, Enhanced spontaneous
nucleation of diamond nuclei in hot and cold microwave plasma systems, Phys. Status Solidi B 250,
No. 12, 2753–2758 (2013).
Low temperature diamond synthesis
Diamond layer ultrasonically seeded by ultradispersed detonation diamond (UDD) powder on Si (10x10
mm). Pressure 0.1 mbar, deposition time 15 h, gas mixture 2.5% of CH4 and 10% of CO2 in H2.
Temperature regulated by plasma power and table heater.
Tibor Izak, Oleg Babchenko, Marian Varga, Stepan Potocky and Alexander Kromka, Low temperature
diamond growth by linear antenna plasma CVD over large area, Phys. Status Solidi B 249, No. 12,
2600–2603 (2012).
Carbon nanotubes synthesis
High temperature methods
-Arc discharge between grapthite electrodes
-Graphite target laser ablation
-high temperature (3500 °C), short growth time ms, SWCNTs require catalyst –
transition metal (Fe,Ni,Co,Mo), carbon diffuses into catalytic particle and
precipitates out in the form of nanotube, several nanotubes can growth from
one particle
K.B.K. Teo, R.G. Lacerda et al.. "Carbon Nanotube Technology for Solid State and Vacuum
Electronics" IEE Proceedings in Circuits, Devices and Systems (Nanoelectronics issue) 151, 443
(2004).
Carbon nanostructures synthesis
Low temperature methods – thermal CVD, PECVD (rf, mw, dc, hf)
hydrocarbon decomposition in presence of catalyst
Temperature 500-1200 °C, longer deposition times- minutes even hours, transition
metal catalyst plays significant role and serves as template for nanotube growth
PECVD – lowering deposition temperature, compatibility with microelectronics
industry, electric field vertical alignment (0.15 V/mm)
M. Meyyappan, L. Delzeit, A. Cassell, D. Hash. Plasma Sources Sci. Technol. 12,
205 (2003), M. Meyyappan, J. Phys. D: Appl. Phys. 42 (2009) 213001
• Transition metal catalyst – Fe,Co,Mo,Ni or combination - finite solubility in C leads to CNTs
growth by diffusion, saturation and precipitation mechanism
• Catalyst must be in the form of particles, particles and their surface atoms have high mobility in
nm scale even if the metal is in solid state and can behave like liquid
• in lower temperature surface diffusion dominates, in higher volume diffusion
• Support catalyst (evaporation, sputtering, wet catalyst, colloids etc.) or floating catalyst –
decomposition of organometallics
• Catalyst poisoning effect – covering the particle with amorphous carbon
K. B.K. Teo, C. Singh, M. Chhowalla, W. I. Milne, Encyclopedia of Nanoscience and Nanotechnology, Vol. 10,
Eds. H.S. Nalwa, American Scientific Publishers, Los Angeles, 2003
Catalyst in PECVD
CNTs growth in PECVD systems
DC glow discharge resistively heated carbon electrode – cathode with the sample (Si/SiO2 buffer
layer and Ni catalyst 0.5-20 nm) Anode (2 mm diameter by 1 cm length copper wire) was 2 cm from
cathode. Sample heated to 750 C under H2 and held at this temperature for 15 minutes after that
200 sccm of NH3 was introduced to pressure of 465 Pa. The deposition was carried out in mixture of
C2H2 and NH3 for 15 minutes.
Chhowalla et al., Growth process conditions of vertically aligned carbon nanotubes
using plasma enhanced chemical vapor depositionJ. Appl. Phys., Vol. 90, No. 10,
2001,5308 /
CNTs growth in PECVD systems
2 nm Ni catalyst
NH3 flow at 100 sccm
CNTs growth in PECVD systems
S. Hofmann, C. Ducati, and J. Robertson, B. Kleinsorge, Low-temperature growth of carbon nanotubes
by plasma-enhanced chemical vapor deposition, Appl. Phys. Lett., Vol. 83, No. 1, 135.
DC discharge between the heater stage (cathode)
and the gas shower head (anode), 2 cm above the
stage was ignited by applying a fixed voltage of 600
V.
Si/SiO2/Ni (6 nm) substrate
Samples annealed in 120 Pa NH3 for 15 minutes.
Deposition carried out in C2H2:NH3 50:200 sccm at
150 Pa for 30 minutes.
CNTs growth in PECVD systems
RF (13.56 MHz) capactive coupled discharge with 4 inch
quartz tube. Sample Si/SiO2/Fe Ferritin or 0.1 nm Fe by
electron beam evaporation of Fe 40 cm from the coil in the
furnace. Sample annealed in in Ar to 600 °C and then 60
sccm Ar/CH4 (80%) at 67 Pa. Plasma was turned on for 3
minutes with 75 W power.
No CNTs without the plasma.
Y. Li et .al. , Preferential Growth of Semiconducting SingleWalled
Carbon Nanotubes by a Plasma Enhanced CVD
Method, Nano Lett., Vol. 4, No. 2, 2004, 317.
Possible negative influence of plasma in PECVD
Jeong et al., Appl. Phys. A 79, 85 (2004)
Kinoshita H. et.al., Carbon 42 (2004) 2735