Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 4: II-VI semiconductors

HL 4.4: Vortrag

Montag, 23. März 2009, 11:00–11:15, POT 51

Lifting of the fundamental cavity mode polarization degeneracy in CdSe/ZnSSe-quantum dot monolithic microcavities — •Moritz Seyfried, Joachim Kalden, Kathrin Sebald, Jürgen Gutowski, Arne Gust, Carsten Kruse, and Detlef Hommel — Institue of Solid State Physics, University of Bremen, P.O. Box 330 440, D-28334 Bremen, Germany

Lifting polarization degeneracy of the fundamental cavity mode in a quantum dot (QD)-based microcavity (MC) would allow to control the polarization state of the emitted photon in single-photon emitters. To realize devices in the blue to green spectral region, CdSe QDs were embedded in a monolithic ZnSSe based VCSEL structure grown by molecular beam epitaxy. Circular pillar MCs with diameters in the range from 500 nm up to 4000 nm were prepared by focused-ion-beam etching. Polarization dependent investigations of the fundamental cavity mode reveal a lifting of its degeneracy concerning the polarization. By an appropriate adjustment of the polarizer the two orthogonally polarized components of the fundamental mode can be observed individually with an energy splitting of up to 0.42 meV and quality factors of up to 7800. In any polarization orientation in between a superposition of both modes is detectable. Furthermore, an increase of the energy splitting with increasing pillar diameter is observed. As the MCs are nearly perfectly circular, a lifting of the mode degeneracy due to an elliptical cross-section of the pillars is very unlikely. Therefore, the existence of strain within the MCs as origin of the mode degeneracy is considered and tested by studying the influence of annealing.