Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 71: Quantum Dots: Optical Properties

HL 71.3: Vortrag

Donnerstag, 17. März 2011, 10:45–11:00, POT 251

Built-in dipole moments of InGaN/GaN single quantum dot excitons — •Irina A. Ostapenko, Christian Kindel, Gerald Hönig, Sven Rodt, André Strittmatter, Axel Hoffmann, and Dieter Bimberg — Institut für Festkörperphysik, TU Berlin, Hardenbergstr 36, 10623 Berlin, Germany

We report on direct determination of intrinsic dipole moments of excitonic complexes in InGaN/GaN quantum dots from cathodoluminescence experiments. Single nitride-based QDs show large potential as sources of entangled photon pairs at room temperature for quantum information processing and cryptography applications [1]. The built-in piezoelectric and pyroelectric fields tremendously affect electro-optical properties of nitride heterostructures [2]. The insight into interplay between confined charge carriers and electric fields is crucial for improvement and control of nitride QD-based devices. Only in cathodoluminescence we observe a re-occurring characteristic pattern in temporal traces of emission lines and explain this feature with a model of interaction between an exciton in a quantum dot and a gradually changing electric field of a charge carrier, moving through the material. We derive the magnitude of the built-in excitonic dipole moments as 0.7-7*10-28C*m*0.3-3 e*nm. These values are in good agreement with calculations based on 8-band k*p, extended by a self-consistent Hartree formalism. [1] C. Kindel, S. Kako, T. Kawano, H. Oishi, Y. Arakawa, G. Hönig, M. Winkelnkemper, A. Schliwa, A. Hoffmann, and D. Bimberg, Phys. Rev. B 81, 241309(R) (2010) [2] M. Winkelnkemper, A. Schliwa, and D. Bimberg, Phys. Rev. B 74,155322 (2006)