AIP Digital Archive
A time-dependent finite-difference beam propagation method is presented to analyze quantum interference transistor (QUIT) structures, employing the Aharonov–Bohm effect, in both steady state and transient conditions. Current–voltage characteristics of two ring structures having 0.2 and 0.05 μm channel lengths, respectively, are presented. Additionally, the wave functions are calculated, and reflections are observed in both the ON and OFF states of the device. Cutoff frequency fT values of 3 and 8.5 THz, respectively, are calculated from the switching response to a gate pulse of 200 fs, for the 0.2 μm device, and to a pulse of 50 fs, for the 0.05 μm device. Results indicate that reflections at the drain may degrade frequency performance of these devices, which is not evident from earlier analytical studies. These structures are further explored to investigate the effects of imperfections introduced in fabricating the quantum wire channels. We compare two QUITs, one realized by a 1 nm resolution lithography process (representing an advanced fabrication technique) and the other realized by a 10 nm resolution (representing current state-of-the-art lithography). We also present an asymmetric 10 nm resolution structure, to represent the case when errors in fabrication significantly alter the QUIT topology. This simulation shows strong dependence of the electron transmission probability on the channel topology and roughness determined by the lithographic resolution. © 2000 American Institute of Physics.
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