Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 43: Poster Session: Quantum Dots and Wires - Preparation and Characterization / Devices (incl. Laser) / Ultrafast Phenomena

HL 43.10: Poster

Tuesday, March 27, 2012, 09:30–12:30, Poster D

Capacitance-Voltage spectroscopy of InAs quantum dots under external applied strain — •Sascha René Valentin, Arne Ludwig, Dirk Reuter, and Andreas D. Wieck — Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstrasse 150, D-44780 Bochum

Self-assembled InAs quantumdots (QDs) are integrated on a variety of interesting optical and electronic devices and are also highly interesting from a fundamental point of view. Electric fields are often used to tune the optical and electronic properties of QDs. Just recently it has been shown that external applied strain can reversibly shift the optical emission energy of QDs. Theoretical calculations indicate that the shift in the emission energy originates rather in the changed Coulomb interaction between the charge carriers than in the shift of the energy levels themselves. In this project we want to directly measure the interaction energies of the carriers using capacitance voltage (CV) spectroscopy. In the device we present, a thin electrically contacted CV-membrane is bonded to a PMNPT-piezoelectric actuator. This allows to apply strain to the QDs. The devices are equipped with ohmic contacts and Schottky gates and thus enable electrical measurements of a QD ensemble. CV results for a membrane sample are presented.