Exciton luminescence of spherical GaAs nanocrystals studied by persistent hole-burning spectroscopy

We have studied free-exciton photoluminescence (PL) properties of spherical GaAs nanocrystals embedded in SiO2 matrices fabricated by ion-beam synthesis. Under resonant excitation at energies within the free-exciton PL band, LO-phonon structures appear in the PL hole-burning spectra. By deuterium implantation to GaAs nanocrystals, both the impurity-related PL band and the LO-phonon-assisted luminescence disappear. It is concluded that the exciton–LO-phonon coupling in GaAs nanocrystals is enhanced by local electric fields caused by impurities ionization.