Site-specific growth and density control of carbon nanotubes by direct deposition of catalytic nanoparticles generated by spark discharge

Abstract

Catalytic iron nanoparticles generated by spark discharge were used to site-selectively grow carbon nanotubes (CNTs) and control their density. The generated aerosol nanoparticles were deposited on a cooled substrate by thermophoresis. The shadow mask on top of the cooled substrate enabled patterning of the catalytic nanoparticles and, thereby, patterning of CNTs synthesized by chemical vapor deposition. The density of CNTs could be controlled by varying the catalytic nanoparticle deposition time. It was also demonstrated that the density could be adjusted by changing the gap between the shadow mask and the substrate, taking advantage of the blurring effect of the deposited nanoparticles, for an identical deposition time. As all the processing steps for the patterned growth and density control of CNTs can be performed under dry conditions, we also demonstrated the integration of CNTs on fully processed, movable silicon microelectromechanical system (MEMS) structures.

Dry and Direct Deposition of Aerosol-Synthesized Single-Walled Carbon Nanotubes by Thermophoresis

“…Here, we have, for the first time, systematically studied the direct deposition of SWCNT aerosols by thermophoresis. In general, thermophoretic deposition of aerosol nanoparticles is a promising method for the fabrication of nanoparticle thin films and coatings and catalyst preparation for CVD growth processes on surfaces. , Thermophoretic precipitators (TPs) can be designed so that the deposition efficiency can almost reach unity and the substrate can be kept under near-ambient conditions, meaning that deposition can be carried out on practically any flat substrate, including mechanically or chemically sensitive materials and flexible polymers.…”

Construction of Medusa‐Like Adhesive Carbon Nanotube Array Induced by Deformation of Alumina Sheets

“…For this reason, it is common to start the change before growth by using masks, [ 13 ] photolithography [ 14 ] or inkjet printing [ 15 ] techniques to pattern the catalyst, or laser interference ablation to selectively remove specific regions of catalyst [ 16 ] to form a desired pattern, and then growing arrays of corresponding patterns. Alternatively, some post‐growth techniques are also employed, like the micromechanical bending process, [ 17 ] which bends and flattens the desired regions of surface nanotubes with the movement of a high‐speed rotating tool; transferring/imprinting some of the nanotubes by micro molds; [ 18,19 ] or laser/electron beam ablation to remove partial array, to process the array into a desired structure.…”

Wafer-Scale Thermophoretic Dry Deposition of Single-Walled Carbon Nanotube Thin Films

“…TPs have been previously used to evaluate the aerosol size distributions and exposures to nanoscale aerosols, , and to deposit functional coatings of aerosol-synthesized nanoparticles, ,, FC-CVD SWNTs and catalyst nanoparticles for supported CVD growth of SWNTs, , but to date, no reports of SWNT TCFs fabricated using thermophoretic deposition have been published. With the exception of a design by Holunga et al, capable of uniform deposition on a stationary 150 mm wafer, TPs reported in the literature are typically designed for sampling on microscopy grids or similar small substrates.…”