Time-resolved spectroscopy of irradiated n-GaAs

Gallium arsenide films were grown by the metallorganic chemical vapour deposition method and doped n-type with silicon to concentrations of 2×10¹⁵ and 2×10¹⁶ cm^-3. The lifetime (τ) of the band-to-band recombination process was measured at 77 K using an optical time-resolved spectroscopy technique. The pre-irradiated values ranged from 350 to 550 ps. The samples were irradiated at room temperature with ⁶⁰Co gamma rays, fission neutrons, 7 MeV electrons, protons (0.6 to 500 MeV), alpha particles, and lithium and oxygen ions. Degradation constants (K_τ) attributed to non-radiative processes generated by radiation-induced defects are reported. K_τ is compared to the previously published degradation constants associated with the photoluminescence intensity (K_PL) in the continuous mode, and to the previously published introduction rate (b) of the silicon defect at the arsenic site (Si_As) K_τ, K_PL and b(Si_As ) are compared to non-ionizing energy loss calculations and to the Rutherford scattering theory of the cross-section