Three-dimensional (3D) photonic crystals entirely consisting of GaN have been fabricated for the first time. Detailed investigations of optical Bragg diffraction spectra have shown a high quality of the prepared photonic crystals.
Exciton-polariton photoluminescence kinetics under short-pulse excitation in pure epitaxial GaAs has been investigated. The observed delayed onset of the polariton luminescence is attributed to the energy relaxation of polaritons and photoexcited electrons. The electron energy relaxation is controlled by inelastic impurity scattering. In an ultrapure sample (ND approximately 1012 cm-3) the maximum of luminescence is reached after a considerable delay of 4 ns. At high repetition rate the next excitation pulse causes a fast quenching of polariton luminescence in the vicinity of exciton resonance due to heating of excitons by photoexcited hot electrons. A model of exciton luminescence kinetics involving exciton-electron interaction has been proposed.
The low temperature photoluminescence of ultra pure GaAs grown by vapour phase
epitaxy was investigated .The free exciton luminescence spectnim of GaAs is described
in the framework of the polari ton theory . An inf luence of the excitation density and
temperature on the polariton luminescence 1 ineshape was studied . Temperature transi
tion from the case of the strong exci ton-photon coupi ing to the case of the weak ex
citon-photon coupl ing was observed . An opportunity of use of the polariton luinines
cence 1 me shape analysis for characterizat ion of pure GaAs crysta 1 s is demoristra