PHOTOREFRACTIVE MEASUREMENTS ON ELECTRON-IRRADIATED SEMIINSULATING GAAS

We present photorefractive measurements at 1.06 mum and 1.3 mum performed in electron-irradiated GaAs. Irradiation with electrons of kinetic energies greater-than-or-equal-to 1 MeV introduces intrinsic electrically active defects which modify the Fermi-level position and allow to modify the electron-hole competition mechanism of the photorefractive effect. Furthermore, it is shown that the optical absorption in the 1.3-1.5 mum spectral range can be increased, which might allow to enlarge the useful spectral range of GaAs towards optical telecommunication windows. The native and irradiation-induced defects are assessed by electron paramagnetic resonance and optical absorption spectroscopy conducted at T = 300 K and 77 K. The direct influence of an irradiation-induced mid-gap defect on the photorefractive effect is experimentally and theoretically demonstrated.