Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 36: Quantenpunkte und -dr
ähte: Optische Eigenschaften III

HL 36.5: Vortrag

Montag, 7. März 2005, 11:00–11:15, TU P164

Shape and Order of Wavefunctions in Uncapped InAs/GaAs Quantum Dots — •A. Schliwa¹, T. Maltezopoulos², M. Morgenstern³, R. Wiesendanger², and D. Bimberg¹ — ¹Institut für Festkörperphysik, Technische Universität Berlin — ²Institute of Applied Physics, University of Hamburg — ³II. Inst. of Physics B, RWTH Aachen University

Recently it became possible to map the shape of electron wave-functions in uncapped InAs/GaAs quantum dots (QDs) by using scanning tunneling spectroscopy (STS) [1]. These measurement revealed an anomalous order of the single particle states in most of the investigated QDs which triggered the here presented theoretical investigations based on the eight-band-k·p model.
The outer shape of the model-QD is specified by using the morphological data, recorded as a byproduct of the STS-method, whilst the composition profile has been treated as variable. Most of the measured QDs are elongated in [110] direction with a larger in-plane anisotropy-ratio at the QD-apex than at the bottom. Therefore the order of the wavefunctions is strongly affected by their position in the QD. The tip induced electric field favours a location at the QD-bottom whereas a high InAs concentration in the upper region makes a position in the QD-apex more favourable. In the first case we find the usual order of wavefunctions: s, p_x, p_y, d whereas in the other case the p_y -state moves behind the d-state.
[1] Maltezopoulos T., Bolz A., Meyer C., Heyn C., Hansen W., Morgenstern M., Wiesendanger R., Phys. Rev. Lett. 91, p.196804 (2003)