Exciton dynamics in homoepitaxial GaN in the picosecond regime

Krzysztof P. Korona

doi:10.1117/12.424730

23 April 2001 Exciton dynamics in homoepitaxial GaN in the picosecond regime

Krzysztof P. Korona

Proceedings Volume 4280, Ultrafast Phenomena in Semiconductors V; (2001) https://doi.org/10.1117/12.424730
Event: Symposium on Integrated Optics, 2001, San Jose, CA, United States

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 (FX_A and FX_B) 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 FX_B up to 1000 ps for the A⁰X. Time constants of FX_A 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 T_X (determined from the slope of the blue wing of the FX peak) decays on a time scale of about 80 ps.

Citation Download Citation

Krzysztof P. Korona "Exciton dynamics in homoepitaxial GaN in the picosecond regime", Proc. SPIE 4280, Ultrafast Phenomena in Semiconductors V, (23 April 2001); https://doi.org/10.1117/12.424730

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