Pulsed growth of vertically aligned nanotube arrays with variable density.
The density of vertically aligned carbon nanotube arrays is shown to vary significantly during normal growth by chemical vapor deposition and respond rapidly to changes in feedstock flux. Pulsing the feedstock gas to repeatedly stop and start nanotube growth is shown to induce density variations up to a factor of 1.6 within ca. 1-2 μm long layers, allowing the synthesis of new array architectures with distinct regions of controllable length and density variation. Z-Contrast scanning transmission electron microscopy of corresponding sections of the arrays is used to provide unambiguous measurements of these density variations. Time-resolved optical reflectivity measurements of the height and optical extinction coefficient of the growing arrays are shown to provide a real-time diagnostic of both array density and growth kinetics.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6488, USA.
Jeremy J
JJ
Jackson
Alex A
AA
Puretzky
Karren L
KL
More
Christopher M
CM
Rouleau
Gyula
G
Eres
David B
DB
Geohegan
D005740:Gases / Q000737:chemistry; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D036103:Nanotechnology / Q000295:instrumentation*; D043942:Nanotubes / Q000737:chemistry*
D005740:Gases