The versatility of catalytic LCVD technique to grow carbon nanotubes

1. The versatility of catalytic LCVD technique to grow carbon nanotubes Iuliana Morjan1,2, Ion Morjan2, Rodica Alexandrescu2, Catalin Luculescu2, Eugeniu Vasile3, Monica Scarisoreanu2, Anca Barbut2 1 IMT-Bucharest, 126A, ErouIancuNicolae street, 077190, PO-BOX 38-160, 023573, Bucharest, ROMANIA 2 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 SYNTHESIS 2ndStep: synthesis of nanotubes by LCVD 1st Step: the preparation of the substrate RESULTS USING SF6 iron corresembeded Fe C catalyst in carbon shells SF6/Ar MIXTURE INFLUENCES Laser beam 12 mm Spin coating deposition There is a compromises between SF6 and Ar mixture LASER POWER AND PRESSURE INFLUENCES ADVANTAGES By increasing PL increase the length of CNT and sometime increase also the thickness By increasing pressure increase the length of CNT 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. >500 m RESULTS USING NH3 Laser beam 1 mm REPRESENTATIVE SEM and TEM IMAGES USING NH3 USING SF6 In order to avoid CNT damage, the temperature was adjusted from 900 oC to about 430 oC (by acting on the laser power) CONCLUSIONS • On the catalytic growth of CNT by LCVD technique: • NH3 additive gas is more efficient than SF6: • unwanted carbon deposits are not formed • the mean diameters are much thinner • The formation temperature is relatively low. At lower pressure CNT are oriented in the direction of gas flow Perspective Acknowledgement: some of the results were obtained in the frame of the Project POSDRU/89/1.5/S/6370