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HL: Halbleiterphysik

HL 12: Quantenpunkte und -dr
ähte: Transporteigenschaften I

HL 12.9: Vortrag

Montag, 26. März 2001, 17:30–17:45, S9/10

Nonlinear electron transport in double quantum dots coupled to confined phonons — •Stefan Debald¹, Tobias Brandes², and Bernhard Kramer¹ — ¹Inst. Theor. Physik, Universität Hamburg, Jungiusstr. 9, 20355 D-Hamburg — ²Dep. of Physics, University of Manchester (UMIST), P.O. Box 88, Manchester M60 1QD, UK

We investigate the influence of electron-phonon interaction on the nonlinear electron transport through a double quantum dot in a free standing quantum well. In (partly) free standing structures, electron transport through double dots is suspected to show signatures of phonon confinement. We assume that such structures represent phonon cavities. With such a model we find by using a numerical approach a staircase-like phonon DOS superimposed by Van-Hove singularities for different cavity mode families.
Using a model by Brandes and Kramer [1] we also calculate the nonlinear inelastic electron current through a double dot at low temperatures. Within this model the transport is mediated by spontaneous emission of phonons. The current-voltage characteristic depends on the orientation of the double dot with respect to the geometry of the cavity. Moreover, it is possible to determine the family of the emitted phonons by the dot orientation. We show that the signatures of the confinement in the phonon DOS also show up in the electronic transport. The characteristic separation of the staircase-like features is determined by the cavity width. Therefore, it should be possible to detect the predicted phonon confinement effects in the electron current.
[1] T. Brandes and B. Kramer, Phys. Rev. Lett. 83, 3021 (1999)