Radiation Effects in Optical Emitters and Receivers

摘要

In some applications optoelectronic devices must function in a radiation environment which requires knowledge of the manner and extent of expected device degradation upon exposure to radiation. An up-to-date summary of radiation damage studies on the emitter and detector components of optoelectronic systems: Light-emitting diodes (LEDs), laser diodes, semiconductor detectors, and optical isolators. Some conclusions drawn from this work are: (1) Amphoterically Si doped GaAs LEDs are extremely sensitive to irradiation and should be avoided except in those applications where the fluence and/or dose levels are low and changes in emitter output can be tolerated. (2) The most important pre-irradiation parameters for judging LED radiation degradation are the minority carrier lifetime, tau sub 0 , and the output power P sub 0 . By controlling tau sub 0 with radiative recombination processes one can minimize the radiation sensitivity and, at the same time, maintain large P sub 0 values. (3) Laser diodes when operated well into lasing conditions are insensitive to irradiation and therefore attractive for radiation environment applications. (4) Detectors which depend on diffusion-limited collection of carriers for photocurrent generation are sensitive to irradiation and should be avoided. (5) Recent data shows that certain actively biased avalanche photodiodes do not catastrophically fail during ionization pulses as large as 1 x 10 exp 10 rads/sec, and therefore, these devices should be considered for radiation applications. (6) For future systems operating at wavelengths greater than 1.0 mu m, III--V compound detectors with thin active regions are more attractive than Si detectors. (7) Finally, many commercial optical isolators are made up of amphoterically Si doped GaAs LEDs and phototransistors. Since both of these devices are radiation sensitive, such isolators are not suitable for radiation environments. (ERA citation 04:024396)