Physical Review B 50, 5528-5544 (1994)

[Issue 8 -- August 15, 1994]

Time-dependent transport in interacting and noninteracting resonant-tunneling systems

Antti-Pekka Jauho
Mikroelektronik Centret, Technical University of Denmark, DK-2800 Lyngby, Denmark
Nordita, Blegdamsvej 17, DK-2100 Copenhagen O, Denmark
Ned S. Wingreen
NEC Research Institute, 4 Independence Way, Princeton, New Jersey 08540
Yigal Meir
Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106

(Received 5 April 1994)

We consider a mesoscopic region coupled to two leads under the influence of external time-dependent voltages. The time dependence is coupled to source and drain contacts, the gates controlling the tunnel-barrier heights, or to the gates that define the mesoscopic region. We derive, with the Keldysh nonequilibrium-Green-function technique, a formal expression for the fully nonlinear, time-dependent current through the system. The analysis admits arbitrary interactions in the mesoscopic region, but the leads are treated as noninteracting. For proportionate coupling to the leads, the time-averaged current is simply the integral between the chemical potentials of the time-averaged density of states, weighted by the coupling to the leads, in close analogy to the time-independent result of Meir and Wingreen [Phys. Rev. Lett. 68, 2512 (1992)]. Analytical and numerical results for the exactly solvable noninteracting resonant-tunneling system are presented. Due to the coherence between the leads and the resonant site, the current does not follow the driving signal adiabatically: a ``ringing'' current is found as a response to a voltage pulse, and a complex time dependence results in the case of harmonic driving voltages. We also establish a connection to recent linear-response calculations, and to earlier studies of electron-phonon scattering effects in resonant tunneling.

©1994 The American Physical Society.

PACS: 73.20.Dx 73.40.Ei 73.40.Gk 73.50.Fq

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