https://doi.org/10.1140/epjb/e2013-30631-5
Regular Article
Thickness dependence of photoluminescence-decay profiles of exciton-exciton scattering in ZnO thin films*
1
Department of Material and Life Science, Division of Advanced
Science and Biotechnology, Graduate School of Engineering, Osaka
University, 2-1 Yamada-oka,
Suita, 565-0871
Osaka,
Japan
2
Venture Business Laboratory, Osaka University,
2-1 Yamada-oka, Suita,
565-0871
Osaka,
Japan
3
Department of Applied Physics, Graduate School of Engineering,
Osaka City University, 3-3-138
Sugimoto, Sumiyoshi-ku, 558-8585
Osaka,
Japan
4
Department of Physical Science, Graduate School of Science, Osaka
Prefecture University, 1-1 Gakuen,
Naka-ku, Sakai, 599-8531
Osaka,
Japan
a e-mail: s.wakaiki@mls.eng.osaka-u.ac.jp
Received:
17
July
2012
Received in final form:
13
February
2013
Published online:
18
September
2013
We have investigated the photoluminescence (PL) dynamics of ZnO thin films under intense excitation conditions using an optical-Kerr-gating method. The PL bands originating from exciton-exciton scattering (P emission) and biexciton (M emission) have been observed at 10 K. The ultrashort gating time of 0.6 ps has enabled us to obtain precise information of the temporal profiles of the peak energies and the intensities of the P- and M-PL bands. We have found that the decay time of the P emission becomes longer with increasing film thickness, while that of the M emission is independent of the film thickness. Although the decay time of the P emission is an increasing function of the film thickness, the relation is not in proportion, which is contrary to the predicted proportionality based on a simple model of photon-like polariton propagation.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2013