the recent experimental
demonstration using Calcium (Ca) as a contact metal to realize the n-type carbon nanotube
field effect transistors (CNTFET). In order to fully optimize this proposed device model,
effects of different parameters like the work function, oxide thickness, the oxide capacitance
and the source velocity limits were studied. Among all the parameters, the work function of
the contact metal plays an important role for controlling the flow of carriers through the
carbon nanotube channel and to reduce the threshold voltage. A semi-classical simulation of
the proposed n-type CNTFET has been performed. Results show an excellent subthreshold
swing value of 62.91 mV/decade, close to the International Technology Roadmap for
Semiconductor (ITRS) specifications.
transistors. The carbon nanotube field effect transistors (CNTFETs) are excellent candidates
for the current microelectronic technology that exhibits improved performance in
nanometer-regime. Intense research is in progress to study the transport properties of carbon
nanotube based field effect transistors. Due to the ability of ballistic transport, CNTFETs
have been studied in recent years as a potential alternative to CMOS devices [1, 2]. It is
shown that these CNTFETs can be made with ohmic or Schottky type contacts [3, 4]. The
operation of Schottky contact CNTFETs is by modulating the transmission coefficient of
the barriers at the contact between the metal and the CNT . It has been observed that
ambipolar conduction (both holes and electron conduction) is the matter on which to focus
in these type of devices. Due to the ambipolar conduction of Schottky barrier CNTFETs, the
Ion/Ioff ratio is limited.
Phys. Lett., 2005, 86, 153108.
2. M. Pourfath, E. UngersbÃ?ï¿½Ã¯Â¿Â½ck, A. Gehring, B.-H. Cheong, W. Park, H. Kosina, S.
Selberherr, proceeding of the 34th European Solid-State Device Research
Conference,Ã?ï¿½Ã?Â® Institute of Electrical and Electronics Engineers, 2004, 429.
3. R. Martel, V. Derycke, C. Lavoie, J. Appenzeller, K. Chan, J. Tersoff and P.
Avouris, Ã?ï¿½Ã?Â¬Ambipolar electrical transport in semiconducting single-wall carbon
nanotubes,Ã?ï¿½Ã?Â® Phys. Rev. Lett., vol. 87, no. 25, pp. 256807, 2001.
4. J. Appenzeller, J. Knoch, V. Derycke, R. Martel, S. Wind, and P. Avouris, Phys. Rev.
Lett., 2002, 89, 126801.
5. Z. Ren, Ph. D. Thesis, Purdue University, West Lafayette, IN, Dec. 2001.
6. J. Gou and M. Lundstrom, IEEE Trans. On Electron Devices, vol. 49, issue 11, pp.
7. Y. Nosho, Y. Ohno, S. Kishimoto, and T. Mizutani , Appl. Phys. Lett., vol. 86, pp.
073105, Feb. 2005.
8. H. Ishii, Sugiyama, E. Ito and K. SekiAdv. Mater. (Weinheim, Ger.), vol. 11, pp. 605,
9. A. Javey, J. Gou, D. B. Farmer, Q. Wang, D. Wang, R. G. Gordon, M. Lundstom,
and H. Dai, Nano letter, vol. 4, no. 3, pp. 447-450, 2004.
10. FETToy2.0 tool information,
11. K. Natori, J. Applied Phys., vol. 76, no. 8, 15 Oct., 1994.
12. International Technology Roadmap for Semiconductor, 2001 Edition, Semiconductor
Industry Association, Ã?ï¿½Ã?Â¬www.itrs.net,Ã?ï¿½Ã?Â® 10/03/2005.
13. A. Javey, J. Gou, Q. Wang, M. Lundstrom, H. Dai, Nature, 2003, 424, 654
ECEB51, Mobile, AL, 36688
2ECE, University of south Alabama, 307 university Blvd., Mobile, AL, 36688
3Mechanical Engineering, University of South Alabama, 307 University Blvd., Mobile, AL,36688
Researchers should cite this work as follows: