Recombination characteristics of the proton and neutron irradiated semi-insulating GaN structures

Variations of the photoluminescence spectra and photoconductivity transients with proton and neutron fluence in the semi-insulating GaN-layered structures of different thickness are examined. It has been obtained that the intensity of the photoluminescence bands associated with grown-in defects of the semi-insulating GaN layers decreases non-linearly with irradiation of high-energy proton and neutron fluence in the range of 1014-1016 cm-2. The recombination and trapping lifetimes also exhibit a significant decrease with fluence which is most prominent in thin epilayers. Defect parameters determined from lifetime variations with temperature and from the relative changes of the photoluminescence bands are discussed