306 research outputs found
Delay and distortion of slow light pulses by excitons in ZnO
Light pulses propagating through ZnO undergo distortions caused by both bound
and free excitons. Numerous lines of bound excitons dissect the pulse and
induce slowing of light around them, to the extend dependent on their nature.
Exciton-polariton resonances determine the overall pulse delay and attenuation.
The delay time of the higher-energy edge of a strongly curved light stripe
approaches 1.6 ns at 3.374 eV with a 0.3 mm propagation length. Modelling the
data of cw and time-of-flight spectroscopies has enabled us to determine the
excitonic parameters, inherent for bulk ZnO. We reveal the restrictions on
these parameters induced by the light attenuation, as well as a discrepancy
between the parameters characterizing the surface and internal regions of the
crystal.Comment: 4 pages, 4 figure
Mie-resonances, infrared emission and band gap of InN
Mie resonances due to scattering/absorption of light in InN containing
clusters of metallic In may have been erroneously interpreted as the infrared
band gap absorption in tens of papers. Here we show by direct thermally
detected optical absorption measurements that the true band gap of InN is
markedly wider than currently accepted 0.7 eV. Micro-cathodoluminescence
studies complemented by imaging of metallic In have shown that bright infrared
emission at 0.7-0.8 eV arises from In aggregates, and is likely associated with
surface states at the metal/InN interfaces.Comment: 4 pages, 5 figures, submitted to PR
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