Controlled Growth of Single Walled Carbon Nanotubes (SWNTs) for Nanoelectronics:

1. Growth of High-Density Parallel Arrays of Long SWNTs on Quartz Substrates.

We developed a CVD approach to prepare high-density and perfectly aligned arrays of long SWNTs on stable temperature (ST)-cut quartz substrates using copper as the catalyst and ethanol as the carbon source [Lei Ding et al., JACS, 2008]. Compared with earlier reports, we have demonstrated that the aligned nanotube arrays can be grown on ST quartz substrate without the need of thermal annealing. The density can reach >50 nanotubes per micron and the length can be a few millimeters. Such high density aligned nanotube films can find immediate applications in high current and high frequency devices. Additionally, we have obtained direct proof on the tip-growth mechanism for the aligned nanotubes and important evidence that explained the termination of the growth.





2.
Selective Growth of High-Density, Well Aligned Semiconducting SWNT Arrays.

We made much new progress in selective growth of high-density, well aligned semiconducting SWNT arrays on surface [Lei Ding et al., Nano Letters, 2009]. Raman spectroscopy together with electrical measurements of field effect transistors (FETs) fabricated from the as-grown samples showed that over 95% of nanotubes in the arrays are semiconducting. The mechanism of selective growth was explored. It is proposed that introducing methanol in the growth process, combined with the interaction between the SWNTs and the quartz lattice, leads to the selective growth of aligned semiconducting nanotubes. Such a high density of horizontally aligned semiconducting SWNTs can be readily used in high current nanoFETs and sensors. This method demonstrates great promise to solve one of the most difficult problems which limits application of carbon nanotubes in nanoelectronics - the coexistence of metallic and semiconducting nanotubes in samples produced by most, if not all, growth methods.


3. Devices and Sensors of aligned SWNTs.

We fabricated high performance field electron transistors (FETs) with the as-grown aligned nanotube arrays on quartz substrates. The FETs were fabricated with a top gate method. A solid conducting polymer (poly (ethylene oxide)/lithium perchlorate mixture (PEO:LiClO43H2O)) was utilized as the top gate. The on/off ratios of the FETs were between 50 and 90. Though there is still some room to improve the performance of the devices, the well aligned semiconducting SWNT arrays show their wide potential applications in nanoFETs and sensors.





 

Contact Information

Dr. Jie Liu
Department of Chemistry
Duke University
2105 French Family Science Center
Durham, NC, 27708-0354
Tel: (919) 660-1549
Fax: (919)660-1605
Email: j.liu@duke.edu

Available Positions:

For available positions, please contact Dr. Jie Liu at j.liu@duke.edu for more information

 

 

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