Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 38: ZnO I

HL 38.7: Vortrag

Donnerstag, 29. März 2007, 11:45–12:00, H17

A Zincoxide Microwire Laser — •Christian Czekalla, Andreas Rahm, Jörg Lenzner, and Marius Grundmann — Universität Leipzig, Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, Linnéstr. 5, 04103, Leipzig, Germany

We report the observation of stimulated emission from hexagonally shaped zinc oxide (ZnO) microcrystals observed by spatially resolved photoluminescence (PL) and high excitation spectroscopy. The structures were synthesized by thermal evaporation of a pressed ZnO-graphite target at ambient pressure. They show a high PL signal under low excitation conditions. Under high optical excitation, the observed PL spectra show an additional peak at 3,15 eV. This is most probably related to an inelastic exciton-exciton scattering process (P-band). The gain reported for ZnO [1] cannot overcome the high losses caused by the short distance of the mirrors. Hence, ZnO microwires per se cannot be expected to act as a cavity for the emitted light. However, stimulated emission as a result of single pass gain will be demonstrated. A superlinear dependency of the peak intensity on the excitation and the observed spectral narrowing indicate lasing with a threshold of 150 kW/cm².

[1] Y. Chen et al, Appl. Phys. Lett. 78, 11 (2001).