Time-resolved spectroscopy of irradiated n-GaAs

Abstract

Gallium arsenide films were grown by the metallorganic chemical vapour deposition method and doped n-type with silicon to concentrations of 2/spl times/10/sup 15/ and 2/spl times/10/sup 16/ cm/sup -3/. The lifetime (/spl tau/) 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 /sup 60/Co gamma rays, fission neutrons, 7 MeV electrons, protons (0.6 to 500 MeV), alpha particles, and lithium and oxygen ions. Degradation constants (K/sub /spl tau//) attributed to non-radiative processes generated by radiation-induced defects are reported. K/sub /spl tau// is compared to the previously published degradation constants associated with the photoluminescence intensity (K/sub PL/) in the continuous mode, and to the previously published introduction rate (b) of the silicon defect at the arsenic site (Si/sub As/) K/sub /spl tau//, K/sub PL/ and b(Si/sub As/) are compared to non-ionizing energy loss calculations and to the Rutherford scattering theory of the cross-section.