Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 95: Poster IV B (Quantum dots and wires: Prepration, characterization, optical properties, and transport)

HL 95.26: Poster

Donnerstag, 19. März 2015, 14:00–20:00, Poster B

Resonant tunneling current through energy levels of strain induced quantum dots — •Daming Zhou, Andreas Beckel, Martin Geller, and Axel Lorke — Faculty of Physics and CENIDE, University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany

Strain-induced quantum dots (SIQD) confine electrons and holes to a lateral potential minimum within a nearby quantum well (QW) layer. The potential minimum can be introduced by a self-assembled quantum dot layer. SIQD have a much weaker confining potential than the self-assembled quantum dots. Their discrete energy levels have been demonstrated by optical measurements previously.

In this experiment, we pattern a two-dimensional electron gas with adjacent quantum dots into a field-effect transistor structure, in which a pair of metal split gates define the conduction channel in the QW layer. We observe a group of resonant current peaks when the free electrons in the constriction are depleted completely by application of deep negative voltage. Firstly, we can determine the SIQD space locations between the slit, by scanning the active area from one side to another using an antisymmetric bias contribution applied to the sides of the split gates. Furthermore, by varying the symmetric gate voltage contribution we can align the energy levels in the SIQD with the Fermi energy to allow transport through the SIQD. This way, we can study not only how one resonant energy level follows the two side gates, but also, from the energy level space, it is possible to learn about the Coulomb blockade effect of electrons inside the dot.