Synthesis of Bandgap-Controlled Semiconducting Single-Walled Carbon Nanotubes

Abstract

Bandgap-controlled semiconducting single-walled carbon nanotubes (s-SWNTs) were synthesized using a uniquely designed catalytic layer (Al(2)O(3)/Fe/Al(2)O(3)) and conventional thermal chemical vapor deposition. Homogeneously sized Fe catalytic nanoparticles were prepared on the Al(2)O(3) layer and their sizes were controlled by simply modulating the annealing time via heat-driven diffusion and subsequent evaporation of Fe at 800 degrees C. Transmission electron microscopy and Raman spectroscopy revealed that the synthesized SWNTs diameter was manipulated from 1.4 to 0.8 nm with an extremely narrow diameter distribution below 0.1 nm as the annealing time is increased. As a result, the bandgap of semiconducting SWNTs was successfully controlled, ranging from 0.53 to 0.83 eV, with a sufficiently narrow energy distribution, which can be applied to field-effect transistors based on SWNTs.

Diameter control of single-walled carbon nanotube forests from 1.3–3.0 nm by arc plasma deposition

“…From a literature survey, the floating catalyst method has demonstrated the widest and most precise control of SWCNT diameter (~<1 to ~2.1 nm)456. In addition, previous approaches, which used the sparse distribution of catalysts on substrates, have demonstrated a coarse control over a substantial diameter range78910. Recently, the diameter control of SWCNT forests has also showed remarkable progress3334353637.…”

“…For substrate growth, one basic approach has demonstrated the widest range of diameter control: increase catalyst spacing to minimize unwanted particle aggregation7891011. In this manner, Lu et al reported diameter control of SWCNTs from 0.6 to 2.1 nm by selectively activating either the smaller or larger nanoparticles7.…”

“…Durrer et al used centrifugation method to separate the nanoparticles prior to deposition to control the diameter with a narrow distribution8. Song et al achieved a narrow distribution of 0.1 nm with diameter control from 0.8 to 1.4 nm by using a sandwiched catalyst system9. Chen et al controlled the diameter of CNTs from 0.9–1.8 nm by controlling the size of SiO 2 nanoparticles10.…”

Controlling the diameter of aligned single-walled carbon nanotubes on quartz via catalyst reduction time

“…Optimization of the pre-annealing conditions or multiple growth cycles with argon purge steps between each growth cycle led to higher SWCNT densities [22,23]. The reduction of the iron catalyst particle size during annealing has so far only been investigated for vertically aligned SWCNT forests on Al 2 O 3 and random networks [24][25][26].…”

Laser-assisted nanofabrication of carbon nanostructures

“…Since the growth of single-walled CNTs is sensitive to the environmental temperature, 101 a controlled periodic temperature change in the growth process is expected to obtain a periodic change in the diameters of single-walled CNTs, 102 implying the possibility to achieve bandgap engineering within individual single-walled CNTs for the fabrication of functional devices. New electronic and optical properties can be expected from the diameter-modulated single-walled CNTs, such as improved optical absorption in solar cells by absorbing different wavelength regions in the solar spectrum in different sections of the CNTs.…”