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Title: The effect of charged quantum dots on the mobility of a two-dimensional electron gas: How important is the Coulomb scattering?

We have investigated the influence of a layer of charged self-assembled quantum dots (QDs) on the mobility of a nearby two-dimensional electron gas (2DEG). Time-resolved transconductance spectroscopy was used to separate the two contributions of the change in mobility, which are: (i) The electrons in the QDs act as Coulomb scatterers for the electrons in the 2DEG. (ii) The screening ability and, hence, the mobility of the 2DEG decreases when the charge carrier density is reduced by the charged QDs, i.e., the mobility itself depends on the charge carrier concentration. Surprisingly, we find a negligible influence of the Coulomb scattering on the mobility for a 2DEG, separated by a 30 nm tunneling barrier to the layer of QDs. This means that the mobility change is completely caused by depletion, i.e., reduction of the charge carrier density in the 2DEG, which indirectly influences the mobility.
Authors:
; ; ;  [1] ; ;  [2]
  1. Fakultät für Physik and CeNIDE, Universität Duisburg-Essen, Lotharstraße 1, Duisburg 47048 (Germany)
  2. Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum (Germany)
Publication Date:
OSTI Identifier:
22413052
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CARRIER MOBILITY; CHARGE CARRIERS; CONCENTRATION RATIO; COULOMB SCATTERING; ELECTRIC CONDUCTIVITY; ELECTRON GAS; ELECTRON MOBILITY; LAYERS; QUANTUM DOTS; TIME RESOLUTION; TUNNEL EFFECT; TWO-DIMENSIONAL CALCULATIONS; TWO-DIMENSIONAL SYSTEMS