Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 71: Quantum Dots: Optical Properties
HL 71.10: Talk
Thursday, March 17, 2011, 12:45–13:00, POT 251
Transient Differential Reflection Spectroscopy of Single Lateral InGaAs Quantum Dot Molecules — •Christian Wolpert1,2, Lijuan Wang3, Paola Atkinson3, Armando Rastelli3, Oliver G. Schmidt3, and Markus Lippitz1,2 — 1Max-Planck Institut für Festkörperforschung, Stuttgart, Germany — 24. Physikalisches Institut, Universität Stuttgert, Germany — 3Institut für Integrative Nanowissenschaften, IFW Dresden, Germany
We use a reflective all-optical pump-probe technique in order to characterize single lateral quantum dot molecules (QDMs), which are coupled by electron tunneling. By applying a bias voltage along the molecular axis one can control the coupling strength as well as the energies of the confined states. This becomes manifest in a strong dependence of the photoluminescence (PL) spectrum with respect to the bias voltage. The emission can be switched from one dot to the other as one passes the bias value at which the electron states are energetically aligned. Our interest lies in the understanding of this switching behavior. Differential reflection spectroscopy is well suited for this problem, as it does not depend on the emission of a photon but rather probes the QD’s absorption directly. Furhermore one can capture the kinetics of the process by varying the delay time between pump and probe pulses and thus characterize the system beyond PL.