Emission Properties Of Znse-Based Pillar Microcavities At Elevated Temperatures

We present research achievements that advance the development of quantum dot based low threshold vertical cavity surface emitting lasers operating at elevated temperatures. We report on the optical properties of monolithic ZnSe-based pillar microcavities. Measurements were performed on different microcavity structures containing either ZnCdSSe quantum wells or CdSe quantum dots, respectively, as their active region. For the quantum dot based structures, the implementation of additional MgS/ZnSSe barriers yield temperature stability of the quantum dot emission up to room temperature. Microphotoluminescence experiments show an enhanced collection efficiency for the quantum dot emission in spectral resonance with an optical microcavity mode. High quality factors of up to Q=7860 were achieved for quantum dot structures, while for quantum well devices Q = 3500 was reached as being, analyzed by microphotolumnescence and micro-reflectivity spectroscopy. For the quantum well structures, single mode stimulated emission at 510 nm is shown at 280 K under pulsed optical excitation. Threshold reduction with decreasing pillar diameter is observed in accordance to numerical calculations based on microscopic laser theory. The results are promising for the realization of efficient quantum dot based low threshold vertical cavity surface emitting laser devices operating at elevated temperatures in the near future. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim