Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 39: Quantenpunkte und -dr
ähte: Transporteigenschaften I

HL 39.6: Vortrag

Montag, 7. März 2005, 11:15–11:30, TU P-N202

Single electron quantum dots — •Daniel Schröer¹, Andreas K. Hüttel¹, Stefan Ludwig¹, Jörg P. Kotthaus¹, and Karl Eberl² — ¹CeNS und Sektion Physik, LMU München, Germany — ²MPI f. Festkörperforschung, Stuttgart, Germany

We create lateral quantum dots by depleting the two-dimensional electron system of an AlGaAs/GaAs heterostructure using lithographically defined gold gates. An advantage of this lateral approach is the flexibility in number and geometry of leads and gates. Multiple quantum dots can be coupled capacitively or via tunnel barriers. The interdot coupling strengths and the number of electrons per dot are tunable by means of gate voltages. Here, we present measurements on a unique gate design that allows the definition of either a single or a double quantum dot in the few electron limit. By gradually adjusting the gate voltages, we observe a smooth transition from a single dot to a double dot. We quantify the decreasing interdot tunnel coupling using low frequency transport spectroscopy for one and two electrons. The electron number is verified with an additional quantum point contact. Further on, indications of Kondo effect and higher order tunneling processes are investigated in both the single and double dot regime.