Oct 19, 2010
Laser-assisted CVD modulates CNT diameter
Single-walled carbon nanotubes (SWNTs) are one of the most fascinating materials for developing nanoscale electronic and optical devices. They can be either metallic or semiconducting with variable bandgaps depending on their diameters and chiral vectors. These variations have been considered as limiting factors in the application of SWNTs in electronic and optical devices. However, having a single molecule with different electronic properties in different sections seems very attractive for the fabrication of such devices.
Researchers at the University of Nebraska-Lincoln (UNL) have incorporated these variations into individual SWNTs. A laser-assisted chemical vapour deposition (LCVD) method was used to alter the diameters of the SWNTs in different segments due to the inverse relationship between the diameter and growth temperature.
SWNTs with modulated diameters were grown across Mo electrodes to investigate their electronic transport characteristics. Diode-like behaviour of the structures provided clear evidence of bandgap difference at the two ends of the tubes, which is due to the inverse relationship between the diameter and the bandgap in s-SWNTs. This technique demonstrates an easy and convenient approach for fabricating SWNT-based hybrid structures.
The researchers presented their work in the journal Nanotechnology.
About the author
The work was performed at the UNL and supported by the National Science Foundation (NSF), US. Masoud Mahjouri-Samani, Wei Xiong, Yang Gao and Matt Mitchell are currently pursuing their PhD degrees in the Laser-Assisted Nano-Engineering (LANE) Laboratory at UNL under the supervision of Prof. Yongfeng Lu. Dr Yunshen Zhou is a research assistant professor in the Department of Electrical Engineering at UNL. Prof. Jiang is from the Department of Mechanical & Automation Engineering at the Beijing Institute of Technology. Prof. Yongfeng Lu, the Lott University Professor of Engineering at UNL, is the primary investigator of the project.