Damage coefficient associated with free exciton lifetime in GaAs irradiated with neutrons and electrons

Samples irradiated with one MeV and thermal neutrons and with seven MeV and white electrons at various fluences were used to obtain the broadening parameter of the reflectance peak of the free exciton in GaAs at 17 kelvin. The lifetime of the free exciton as a function of the fluence has been explained by a simple kinetics model which applies also to epitaxial layers. The radius associated with the cross section calculated from the damage coefficients is of the order of three to ten times that of the excitons.