Growth interruption studies on vertically aligned 2-3 wall carbon nanotubes by water assisted chemical vapor deposition

Abstract

Highly aligned, 2-3 wall carbon nanotube (CNT) arrays were used to examine the kinetics of CNT growth. A growth interruption method was used to determine the in situ growth rate. The growth interruption method with a water vapor treatment or acetylene treatment during the interruption enabled the production of CNT stacks with different morphologies. The catalytic activity was also monitored using this method. The lifetime of the catalyst was predicted and verified using the catalyst decay model. High temperature metal oxidation behavior using parabolic curve fitting is assigned to the decay process. Details of the analysis are presented.

Distinct termination morphologies for vertically aligned carbon nanotube forests

“…Post-growth delamination of forests has been reported to occur readily with simple processing [32,33], including the use of water [32]. Excessive water vapor exposure during growth has also been observed to cause delamination [14]. It has also been noted that forests tend to fall off the substrate easily [14], which is often the case here.…”

“…Excessive water vapor exposure during growth has also been observed to cause delamination [14]. It has also been noted that forests tend to fall off the substrate easily [14], which is often the case here. Delamination of continuous films during growth has been previously reported [10].…”

“…Millimeter tall forests of SWNTs and/or MWNTs (multi-walled carbon nanotubes) are now regularly synthesized [1,3,[5][6][7][8][9][10][11][12][13][14][15][16][17] and research has shifted focus from how nanotube growth is initiated to the increasingly important question of how nanotube growth terminates [15,18,19]. Several reports demonstrate that nanotube forests grow at an initially rapid rate which drops off either gradually [7,20,21] or suddenly [15,22,23].…”

Effect of buffer layer deposition on diameter and alignment of carbon nanotubes in water-assisted chemical vapor deposition

“…The catalyst rearrangement is in such a way that the CNTs alignment changed with the growth time. However, it was observed that CNT growth follows the bottom growth approach, where Fe catalyst particles attach to the substrate and CNTs grow vertically from them [18,31]. This suggests that the top portion of the CNT forest grew earlier from the randomly arranged catalyst particles while the bottom portion of the CNT forest grew later from the more arranged/modified catalyst particles.…”

Data-driven understanding of collective carbon nanotube growth by in situ characterization and nanoscale metrology

“…For example, optical photography and videography, 67,68 optical interference, 69 single-slit laser diffractography, 70 time-resolved reflectivity, 9 laser triangulation, 71,72 and cycling of growth to create stacked structures visible by SEM. 64,73,74 Importantly, all of the abovementioned methods only enables quantifying the height kinetics. On the other hand, real-time mass measurements are more challenging, and have been achieved in the past generally by using a microbalance either ex situ, 5,75 or in situ.…”