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Proceedings Paper

Exciton dynamics in homoepitaxial GaN in the picosecond regime
Author(s): Krzysztof P. Korona
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Paper Abstract

Time-resolved photoluminescence spectra have been measured for single crystal GaN layers fabricated by metalorganic chemical vapor deposition on GaN single-crystal substrates. The low temperature spectra consist of a donor-bound exciton (D0X) recombination at 3.472 eV, an acceptor bound exciton (A0X) at 3.467 eV and free excitons A and B (FXA and FXB) at 3.478 eV and 3.483 eV, respectively. Below 70 K, the D0K peak dominates. At higher temperatures, delocalization of excitons is observed, and the free exciton emission becomes very strong. At low excitation density (100 W/cm2), the PL decay times in GaN are in the range from 30 ps for the FXB up to 1000 ps for the A0X. Time constants of FXA and D0X are of the order of few hundred ps. They are longest at about T equals 50 K. Decay times of both free and bound excitons become longer at higher excitation densities (above 1 kW/cm2) what is explained by changes in exciton dynamics with the increase of the exciton temperature caused by the laser pulse. The exciton temperature TX (determined from the slope of the blue wing of the FX peak) decays on a time scale of about 80 ps.

Paper Details

Date Published: 23 April 2001
PDF: 11 pages
Proc. SPIE 4280, Ultrafast Phenomena in Semiconductors V, (23 April 2001); doi: 10.1117/12.424730
Show Author Affiliations
Krzysztof P. Korona, Warsaw Univ. and Max-Planck-Institut fuer Festkoerperforschung (Poland)

Published in SPIE Proceedings Vol. 4280:
Ultrafast Phenomena in Semiconductors V
Hongxing Jiang; Kong-Thon F. Tsen; Jin-Joo Song, Editor(s)

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