Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 16: Microcavities

HL 16.9: Talk

Monday, March 14, 2011, 16:45–17:00, FOE Anorg

Polarization properties of the exciton-polariton occupation in ZnO-based microresonators — •Chris Sturm, Helena Hilmer, Steve Linke, Rüdiger Schmidt-Grund, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Linnéstraße 5, 04103 Leipzig

The possibility of the realization of a high temperature Bose-Einstein condensate (BEC), ultra-low threshold lasers and polariton based LEDs makes exciton-polaritons very interesting. Of special interest are ZnO-based microresonators since the formation of exciton-polaritons was observed up to 410 K and the predicted temperature for the formation of a BEC is 610 K [1,2]. Here we report on the influence of the polarization of cavity-photons, which are involved in the exciton-photon coupling, on the occupation of the lower polariton branch in ZnO-based microresonators. From photoluminescence spectra we deduce that scattering of the exciton-polaritons into the states at the bottleneck region is the largest contribution. At negative detuning, the scattering rates are larger for the TM-polarization than for the TE-polarization. This is caused by the TE-TM splitting of the involved cavity-photons. With increasing detuning the difference vanishes and the scattering into the ground state is enhanced (compared to that one into the bottleneck region). Furthermore, we obtained at T=10 K a superlinear dependence of the exciton-polariton occupation on the excitation density for an intermediate detuning regime (|Δ| ≤ 20 meV).

[1] C. Sturm et al., New. J. Phys. 11, 073044 (2009).

[2] S.F. Chichibu et al., Semicond. Sci. Technol. 20, S67 (2005).