Synthesis of multi-walled carbon nanotubes by combining hot-wire and dc plasma-enhanced chemical vapor deposition

Costel Sorin Cojocaru (1) , Dohyung Kim (2) , Didier Pribat (2) , Jean Eric Bouree (2)

1 NanoMaDe
2 LPICM - Laboratoire de physique des interfaces et des couches minces [Palaiseau]

Multi-walled carbon nanotubes (MWCNTs) have been grown on 7 nm Ni-coated substrates consisting of crystalline silicon covered with a thin layer (10 nm) of TiN, by combining hot-wire chemical vapor deposition (HWCVD) and direct current plasma-enhanced chemical vapor deposition (dc PECVD), at 620 °C. Acetylene (C2H2) gas is used as the carbon source and ammonia (NH3) and hydrogen (H2) are used either for dilution or etching. The carbon nanotubes range from 20 to 100 nm in diameter and 0.3 to 5 μm in length, depending on growth conditions: plasma intensity, filament current, pressure, C2H2, NH3, H2 flow rates, C2H2/NH3 and C2H2/H2 mass flow ratios. By combining the HWCVD and the dc PECVD processes, uniform growth of oriented MWCNTs was obtained, whereas by using only the HWCVD process, tangled MWCNTs were obtained. By patterning the nickel catalyst, with the use of the HW dc PECVD process, uniform arrays of nanotubes have been grown as well as single free-standing aligned nanotubes, depending on the catalyst patterning (optical lithography or electron-beam lithography). In the latter case, electron field emission from the MWCNTs was obtained with a maximum emission current density of 0.6 A/cm2 for a field of 16 V/μm.

Mots clés: Carbon nanotubes; Hot-wire assisted direct current plasma-enhanced chemical vapor deposition

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Costel Sorin Cojocaru, Dohyung Kim, Didier Pribat, Jean Eric Bouree. Synthesis of multi-walled carbon nanotubes by combining hot-wire and dc plasma-enhanced chemical vapor deposition. Thin Solid Films, 2006, 501, pp.227-232. ⟨10.1016/j.tsf.2005.07.162⟩. ⟨hal-00541129⟩