a 10-a editie a seminarului national de nanostiinta si nanotehnologie 18 mai 2011 biblioteca...
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A 10-a editie a Seminarului National de nanostiinta si nanotehnologie
18 mai 2011 Biblioteca Academiei Romane
The versatility of catalytic LCVD technique to grow carbon nanotubes
1st Step:the preparation of the substrate
2nd Step:synthesis of nanotubes by LCVD
Sample Ar window
sccm
C2H2
sccm
SF6
sccm
Ar (in mixture)
sccm
Pressure
mbarr
PL
W
Time
min
CNT lenght
1D 1000 30 5 - 80 80 3 3-4 µm 1F 1000 30 10 - 80 80 3 300-400 nm 1E 1000 30 10 5 80 80 3 200 nm 10A 1000 30 15 5 80 80 3 > 500 µm
There is a compromises between SF6 and Ar mixture
SF6/Ar MIXTURE INFLUENCES
LASER POWER AND PRESSURE INFLUENCES
By increasing PL increase the length of CNT and sometime increase also the thickness By increasing pressure increase the length of CNT
Sample Ar window
sccm
C2H2
sccm
SF6
sccm
Ar (in mixture)
sccm
Pressure
mbarr
PL
W
Time
min
CNT lenght
10A 1000 30 15 5 80 80 3 > 500 µm 1-7 1000 30 15 5 80 60 3 110 µm 1-9 400 30 15 5 40 40 3 80 µm
1-18 400 30 15 5 40 30 3 30 µm 1-11 400 15 5 - 40 40 3 40 µm 1-19 400 15 5 - 40 30 3 40 µm 1-12 400 10 5 - 40 40 3 60 µm 1-14 400 10 5 - 40 30 3 2-3 µm
Laser beam 12 mm
Sample Ar windowsccm
C2H2sccm
NH3sccm
Pressurembarr
TemperatureoC
PLW
Timemin
10-7 1000 30 90 100 900 27 210-6 1000 30 90 100 430 13 210-1 1000 30 90 450 430 28 210-2 1000 30 180 100 430 15 210-3 1000 30 180 450 430 20 210-4 1000 30 270 100 430 25 210-8 1000 30 270 450 430 28 2
Laser beam 1 mm
The catalytic LCVD offers the advantage of high versatility and control since it separates the catalyst preparation from the catalytic growth of nanotubes.
The possibility of controlling the size of the laser spot on the substrate allows to heat the substrate very locally and to produce CNTs for various applications.
The high versatility as concerning the catalyst nature and preparation.
A cold wall reactor in which the CO2-laser radiation is heating both the silicon substrate and the gas phase.
High deposition rates, that are favorable for scale-up production of CNTs
LCVD was recently used to fabricate lines of CNTs and to control the orientation of the tubes by use of an electric field
Laser polarization could significantly influence the selective growth of CNTs.
Compared with the post-growth manipulation, the in situ growth is more suitable for large-scale device fabrication.
In order to avoid CNT damage, the temperature was adjusted from 900 oC to about 430 oC (by acting on the laser power)
At lower pressure CNT are oriented in the direction of gas flowOn the catalytic growth of CNT by LCVD technique:On the catalytic growth of CNT by LCVD technique:
1.1.NH3 additive gas is more efficient than SF6: NH3 additive gas is more efficient than SF6:
unwanted carbon deposits are not formed unwanted carbon deposits are not formed the mean diameters are much thinnerthe mean diameters are much thinner
2.2. The formation temperature is relatively low.The formation temperature is relatively low.
Perspective
Iuliana Morjan1,2, Ion Morjan2, Rodica Alexandrescu2, Catalin Luculescu2, Eugeniu Vasile3, Monica Scarisoreanu2, Anca Barbut2
1 IMT-Bucharest, 126A, Erou Iancu Nicolae street, 077190, PO-BOX 38-160, 023573, Bucharest, ROMANIA2 National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor St, P.O. Box MG-36, 077125, Bucharest, Romania
3 METAV-R&D, 31 C.A. Rosetti St., 020011 Bucharest, Romania
Acknowledgement: some of the results were obtained in the frame of the Project POSDRU/89/1.5/S/6370