In situmanipulation and electrical characterization of multiwalled carbon nanotubes by using nanomanipulators under scanning electron microscopy

Abstract

The results of in situ manipulation and electrical transport characterization of individual multiwalled carbon nanotubes ͑MWCNTs͒ grown on a nickel tip by using a piezoelectric nanomanipulation system operating in a scanning electron microscope chamber have been reported. The growth of MWCNT directly on nickel wire by chemical vapor deposition technique ensures good electrical contact with the catalyst substrate. Using the electron beam induced welding, a full characterization of electronic properties of several MWCNTs has been explored without the usual postprocessing methods which may alter, in principle, the intrinsic properties of the carbon nanotube ͑CNT͒. Thanks to the high mechanical and electrical stability ensured by the electron beam welding procedure, a detailed study of the modification of CNT electrical transport properties under CNT buckling has been performed. The crucial role played by the structural defects in determining an irreversibility of a long MWCNT I-V characteristic under mechanical stress has been clearly evidenced. Finally, by a proper sequence of CNT/tip welding and movement, the potential in creating an Ohmic junction between two nanotubes has been demonstrated, opening the route to a systematic investigation of one of the most fundamental aspect of CNT physics.

Tuning electromechanical response of individual CNT by selective electron beam induced deposition

“…The length and outer radius of the MWCNT, as directly determined from the SEM image analysis, are L = 1.2 μm and R o = 20 nm, respectively. According to a previous TEM investigation performed on similarly prepared MWCNTs, the inner radius R i = 5 nm can be reasonably assumed [20]. The CNT tip-metal distance, referred to the nanotube tip position, has been estimated to be H =320±20 nm, the error taking into account the contribution of the Al plate intrinsic roughness and the parallax and focusing being uncertain.…”

“…The resulting CNTs were distributed quite uniformly on the metallic wire surface, sometimes organized in bundles from which free-standing nanotubes were occasionally protruding [20]. Both manipulators were coupled with an external voltage current source.…”

“…Multiwalled carbon nanotubes (MWCNTs) were grown directly on a nickel wire by chemical vapor deposition (CVD) at 700°C, using ammonia and acetylene as the carrier and the precursor gas, respectively (see [20] for further preparation details). The resulting CNTs were distributed quite uniformly on the metallic wire surface, sometimes organized in bundles from which free-standing nanotubes were occasionally protruding [20].…”

“…Alternatively, a selective polymer coating technique has been successfully employed Journal of Non-Crystalline Solids 356 (2010) 2038-2041 for controlling the size of the CNT region effectively involved in the scanning probe detection process [15]. Finally, the electron beam induced deposition (EBID) of amorphous carbon has been qualitatively demonstrated as a versatile method for inducing permanent deformation of the CNT shape, thus allowing the realization of a mechanically stable junction, tips and "nano-hooks" which are extremely useful for a wide range of nanomanipulation processes [20,21].…”

Imaging of charge trapping in distorted carbon nanotubes by x-ray excited scanning probe microscopy

“…2 In such networks, however, unexpected distortions of CNTs at basic subassemblies such as contacts and branches occasionally occur during fabrication. The local distortions modulate the electronic states of CNTs, [3][4][5] resulting in the discontinuity or degradation of electron transport. Knowledge about the origin and cause of electronic modulation in CNT networks is crucial to realize integrated circuits; however, undesirable electronic modulations cannot be easily detected in the images of CNTs obtained by simple microscopic techniques.…”