Carbon nanotube cantilevers on self-aligned copper silicide nanobeams

Abstract

In this letter, the authors describe both a growth method for self-aligning copper silicide (Cu3Si) nanobeams and their use as active catalysts for carbon nanotube (CNT) synthesis via chemical vapor deposition. In the unique geometry of these useful structures, CNT cantilevers are anchored firmly to the Cu3Si nanobeams. The resulting CNT-Cu3Si structures may improve accuracy and reliability of CNT applications in nanoelectromechanical systems.

Growth of Crystalline Copper Silicide Nanowires in High Yield within a High Boiling Point Solvent System

“…Similarly, previous reports using Cu as a seed for elemental Si NW formation have always led the formation of orthorhombic Cu 3 Si catalyst seeds from the initial Cu nanoparticles. [36][37][38] It thus seems likely that pure Si NWs would have been formed in this system had Cu 3 Si crystallites been formed on the Cu substrate rather than Cu 15 Si 4 crystallites. Therefore, the phase of silicide (or germanide) formed on the substrate plays an important role in determining whether pure Si (or Ge) NWs or silicide (germanide) NWs form.…”

“…Two terminal transport measurements acquired between the contacts showed perfect ohmicity and differential conductance (dI/dV) analysis (inset) shows no asymmetry in the curves confirming a purely ohmic transport through the NW. From I-V analysis, the unit resistance was determined to be 266 Ω µm -1 with a corresponding resistivity ρ = ~208 µΩ cm for a Cu 15 Si 4 NW with a ~100 nm diameter, circular cross-section. Additional information on the electrical analysis and an SEM image of the device are presented in the Supporting Information ( Figure S9 for the latter).…”

“…To investigate the importance of Cu diffusion from the underlying Cu substrate in facilitating Cu 15 Si 4 NW growth, reactions were carried out using a 20 nm thick evaporated Cu layer on stainless steel (Supporting Information Figure S9). It was found that Cu silicide crystallites formed on the substrate, however, the lack of a continued Cu source via diffusion from the metal foil resulted in the formation of Cu silicide seeded Si NWs.…”

“…Here, we report the formation of high density arrays of Cu 15 Si 4 nanowires using a high boiling point organic solvent based method. The reactions were carried out using Cu foil substrates as the Cu source with nanowire growth dependent upon the prior formation of Cu 15 Si 4 crystallites on the surface.…”

“…14,15 In nanocrystal morphologies, the predominant phase reported to date has been Cu 3 Si, with nanotriangles, nanosquares and nanorods formed by Cu powder evaporation with and without the presence of an Au catalyst. 16,17 Freestanding Cu 3 Si NWs with diameters between 200 and 300 nm have also very recently been formed using a Ge catalyzed method.…”