Pulsed irradiation of optimized, MBE grown, AlGaAs/GaAs radiation hardened photodiodes

An AlGaAs/GaAs double heterojunction, mesa isolated, photodiode grown by molecular beam epitaxy was irradiated with 18 MeV electrons, 1-10 MeV X-rays, and neutrons from a pulsed reactor. Test results indicate that the AlGaAs/GaAs photodiodes generate approximately 10-20 times less photocurrent during exposure to a pulse of ionizing-radiation than radiation-hardened silicon PIN photodiodes. Studies of neutron induced permanent damage in the AlGaAs/GaAs photodiode show only small changes in optical responsivity and a factor of 8 increase in leakage currents after exposure to 3.6 x 10 to the 15th n/sq cm and 900 krad gamma. The silicon PIN photodiode was exposed to only 28 percent of the fluence used on the AlGaAs photodiodes, and a 40 percent decrease in optical responsivity and a factor of 7000 increase in leakage current have been observed.