Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 37: Quantenpunkte und -drähte: Transporteigenschaften

HL 37.2: Talk

Thursday, March 11, 2004, 10:30–10:45, H13

Wave-function mapping of InAs quantum dots by scanning tunneling spectroscopy — •Theophilos Maltezopoulos, Arne Bolz, Christian Meyer, Christian Heyn, Wolfgang Hansen, Markus Morgenstern, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Jungiusstr. 11, D-20355 Hamburg, Germany

Low temperature UHV scanning tunneling spectroscopy is used to investigate the single-electron states and the corresponding squared wave-functions of individual and free-standing strain-induced InAs quantum dots grown on GaAs(001) by molecular beam epitaxy. Several peaks are found in dI/dV-curves above the dots, which belong to different single-electron states. Spatially resolved dI/dV-images at the peak positions reveal (000)-, (100)-, (010)-, (200)-, and (300)-states, where the numbers describe the number of nodes in [110]-, [110]-, and [001]-direction, respectively. It is found, that the total number and energetic sequence of states is different for different dots. Additionally, the (010)-state is often missing, even when (200)- and (300)-states are present. This electronic anisotropy is attributed to the shape asymmetry of the dots.