Effects of 3 MeV proton irradiation on the excitonic lifetime in gallium arsenide

Gallium arsenide films grown by the metalorganic chemical vapor deposition method and doped n-type with silicon to concentrations of 2 x 1015 and 2 x 1016 cm-3 were exposed at room temperature to 3 MeV proton irradiation in the fluence range 109 to 1014 cm-2. The photoluminescence spectra of the irradiated samples were obtained in the continuous mode. The free exciton transition at 1.515 eV was observed. The lifetime associated with this transition was measured both a/t 4 K and at 60 K, using a time-correlated single photon counting technique. The damage constant associated with the radiative recombination lifetime of the free exciton in GaAs is (7.7 ± 2.2) x 10-3 cm2 s-1 and with the nonradiative lifetime (6.5 ± 2.7) x 10-3 cm2 s-1