Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 9: Poster I

HL 9.85: Poster

Montag, 27. März 2006, 15:15–17:45, P3

Electromigration Forces on Ions in Carbon Nanotube Transistors — •Neng-Ping Wang¹, Stefan Heinze¹, and Jerry Tersoff² — ¹Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany — ²IBM Research Division, T.J. Watson Research Center, Yorktown Heights, New York, 10598 USA

Due to their unique structural and electronic properties carbon nanotubes (CNs) are promising candidates for future nanoelectronics. Recently, field-effect transistors (FETs) from single-wall CNs have been a research focus. In particular, ballistic transport has been demonstrated and key transport parameters compare well with state-of-the-art silicon FETs. Doping with alkali metals has been a main route to improve transistor performance. However, current-induced, electromigration, forces on such alkali ions may lead to ion diffusion and alter the device properties.

Here, we report calculations of ballistic transport in carbon nanotube transistors using the non-equilibrium Greens function formalism within a tight-binding approximation. We use a cylindrically device setup [for details, see S. Heinze, N.-P. Wang, and J. Tersoff, Phys. Rev. Lett. 95, 186802 (2005)] and calculate the current-induced forces on ions located either inside or outside the CN. The forces are largest in the turn-on regime of the transistor, and much smaller in the on- and off-state. The electromigration forces are mainly due to momentum transfer from the charge carriers, i.e., due to the "wind" force. The sign of the "effective valence" Z^* is independent of the actual charge sign, but can be reversed with gate voltage.