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HL: Fachverband Halbleiterphysik

HL 63: Poster: Quantum Dots and Optics

HL 63.74: Poster

Mittwoch, 22. März 2017, 15:00–19:00, P1A

Absorptive lasing mode suppression in highly excited ZnO nano- and microcavities — •Marcel Wille, Tom Michalsky, Chris Sturm, Evgeny Krüger, Marius Grundmann, and Rüdiger Schmidt-Grund — Institut für Experimentelle Physik II, Universität Leipzig, Germany

A variety of lasing experiments in nano- and microstructures reveal different lasing mode energies as well as linewidths for various excitation conditions. However, a conclusive explanation of the resonator mode properties is missing so far. Here, we explain the spectral position and linewidth of lasing modes of three ZnO nano- and microstructures, tetrapod-like nanoparticles, nanowires and microwires. We found that the structure size strongly influences the emission properties. The limited penetration depth of usually used excitation lasers and carrier diffusion lead to an inhomogeneous carrier distribution [1]. Hence, weakly or even nonexcited areas remain present after excitation and lead to strong absorption. This effect is most pronounced for whispering-gallery modes in microwires due to their larger dimensionality. Furthermore, the absorptive lasing mode suppression will be demonstrated for a single nanowire by varying the spot size of the excitation laser. In time-resolved PL measurements we found an ultrafast energy loss of the resonant modes, leading to a linewidth broadening in time-integrated spectra [2]. A model of the time dependent dielectric function fits the experimental observations quite well.

[1] M. Wille et al., Appl. Phys. Lett. 109, 061102 (2016)

[2] M. Wille et al., Nanotechnology 27, 225702 (2016)