Dec 10, 2009
Optical discrimination of metallic carbon nanotubes
Carbon nanotubes (CNTs) have long been the inspiring elements for next-generation nanoscale electronic and optical devices. CNTs have found applications as molecular conductors in the case of metallic CNTs (m-CNTs) and transistors in the case of semiconducting CNTs (s-CNTs). However, due to the mixed growth of both m- and s-CNTs in current synthesis methods, identifying CNTs according to their individual electronic properties is of significant importance for device makers, especially when it comes to ramping up production.
Researchers at the University of Nebraska–Lincoln, US, have developed a convenient approach for selectively removing m-CNTs from CNT mixtures through laser irradiation in the open air. Due to their metallic nature, m-CNTs were found to react differently to s-CNTs and exhibited induced free electron movement and optical near-field enhancement under external laser irradiation, which can be treated as a high-frequency electromagnetic field.
Heat, oxidize and remove
The m-CNTs were selectively heated, oxidized and removed in the open air under certain laser power and wavelength threshold conditions. This technique demonstrates an easy and convenient approach for fabricating s-CNT-based devices that avoids often tedious further purification steps and separation processes. Thanks to its simplicity, the technique offers a scalable route towards the mass production of s-CNT-based devices and electronics.
A full description of the method can be found in the journal Nanotechnology.
About the author
The work was performed at the University of Nebraska–Lincoln (UNL) and supported by the National Science Foundation (NSF), US. Masoud Mahjouri-Samani, Wei Xiong and Yang Gao are currently pursuing their PhD degrees in the Laser-Assisted Nano-Engineering (LANE) Laboratory at UNL under the supervision of Prof. Yongfeng Lu. Matt Mitchell is currently an undergraduate student in the Department of Electrical Engineering at UNL. Dr Yunshen Zhou is a postdoctoral research fellow in the LANE laboratory. Prof. Yongfeng Lu, the Lott Professor of Engineering at UNL, is the primary investigator of the program and director of the LANE laboratory.