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HL: Fachverband Halbleiterphysik

HL 11: Transport: mainly Theory

HL 11.5: Talk

Monday, March 14, 2011, 13:00–13:15, POT 51

Random-telegraph-signal noises due to defects in ballistic nanotube transistors — •Neng-Ping Wang¹ and Stefan Heinze² — ¹Physics Department, Ningbo University, Fenghua Road 818, Ningbo 315211, P.R. China — ²Institute of Theoretical Physics and Astrophysics, Christian-Albrechts-Universitaet zu Kiel, Leibnizstr. 15, D-24098 Kiel, Germany

Recently, there has been remarkable progress in carbon nanotube field-effect transistors (CNFETs). High performance and even ballistic transport have been demonstrated, and there is increasing focus on integrating such transistors into operational device circuits. However, all materials exhibit some low-frequency electrical noise which appears as 1/f noise and random telegraph signals (RTSs). The low-frequency noise increases inversely with the system size, so it is important to understand microscopic aspect of RTS noise in nanotubes.

Here we report calculations of the RTS noises due to single trapped charges in CNFETs using the non-equilibrium Greens function method in a tight-binding approximation. We find that the RTS noise amplitude depends on the nanotube-direction position of the charge. When a trapped charge is farther from the source (or drain) lead and closer to the middle of the channel, the RTS noise in the turn-on regime increases, while the RTS noise in the "on" regime decreases. We calculate the electron potential along nanotube and explain such dependence of the RTS noise. We examine also how the RTS noise depends on both the thickness and dielectric constant of the gate dielectric, suggesting routes to reduce electrical noise.