Radiation effects in light emitting diodes, laser diodes, photodiodes, and optocouplers

A variety of commercially available LEDs, LDs, PDs, and optocouplers from two german manufacturers were irradiated at a flash X-ray source, a 60Co gamma ray source, and a 14 MeV neutron generator. Light output and emission spectrum of the LEDs and LDs were measured before and after irradiation at the 60Co source. With the PDs we measured the dark current and the photo current before and after 60Co irradiation. Determination of the sensitivity against neutrons was made off-line. With PDs we measured the photo current induced by pulsed X-rays. Plastic encapsulated LEDs showed a maximum decrease of output power of 30 dB after a total gamma dose of 10E6 Gy and LDs a theshold current shift of 80 percent after neutron fluences of 4 x 10E14cmE-2 (1 MeV). Irradiations of PDs and APDs with 60Co gammas up to a total dose of 10E6 Gy as well as irradiations with neutrons up to fluences of < 4 x 10E14cmE-2 (1 MeV) led to significant changes of the device parameters. The main effect was a strong inc rease.