Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 37: Quantum Dots and Wires: Optical Properties I (mainly InGaAs Dots)

HL 37.5: Vortrag

Dienstag, 27. März 2012, 11:45–12:00, ER 164

Resonant photocurrent spectroscopy of excited states in a single quantum dot molecule — Florian Klotz¹, •Andreas Waeber¹, Kai Müller¹, Gerhard Abstreiter¹, Hubert Krenner², Martin Brandt¹, and Jonathan Finley¹ — ¹Walter Schottky Institut, Technische Universität München, Deutschland — ²Lehrstuhl für Experimentalphysik I, Universität Augsburg, München

We present resonant photocurrent spectroscopy performed on a single quantum dot (QD) molecule consisting of a pair of vertically stacked self-assembled InGaAs quantum dots. The experiments are performed at low temperature by sweeping the electric field to tune the QD transitions in and out of resonance with an excitation laser kept at a fixed wavelength. Besides the expected anti-crossing of direct and indirect exciton states in the molecule, we observe a series of additional anti-crossings that we identify as arising from coupling of excited excitonic states in the lower dot of the molecule with the orbital ground state of the neutral exciton in the upper dot. Furthermore, the photocurrent spectra yield first indications of non-radiative Förster coupling within the molecule that manifest as weak anti-crossings. We investigate both effects for applied magnetic fields from 0 up to 10 T allowing us to distinguish them via their individual magnetic field dependence.