Regensburg 2002 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 11: Poster 1

HL 11.76: Poster

Montag, 11. März 2002, 17:00–19:30, Poster A

Transport of a HEMT-2DEG structure in the vicinity of InAs-Quantum Dots — •Chr. Weichsel, A.A. Zhukov, W. Thurau, S. Schnüll, Chr. Heyn, and W. Hansen — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Jungiusstraße 11, 20335 Hamburg

We investigate transport properties of a two-dimensional electron system (2DES) in an inverted HEMT structure with a layer of self-assembled InAs-Quantum Dots (QD) in close vicinity. The QDs act as artificial scatterers with tunable charge state. We present results of magnetocapacitance (MC) as well as magnetotransport measurements (MT) on these structures and compare the MC-results with those of InAs QDs in metal-insulator-semiconductor structures. In the MC-data of both structures the Coulomb charging energy for electron injection into s-shell and the presence of the p-shell are well resolved. In frequency dependent MC we find significant enhanced tunnel rates for injection of the second electron into the s-shell. We explain this observation with the contribution of Coulomb interaction potential to the tunnel barrier. MT-measurements in this structure reflect the loading of the QDs in agreement with MC-data. We find a strong density dependence of the electron mobility that in present samples we cannot be correlated to the charging state of the dots.