Impact of neutron irradiation on optical performance of InGaAsP laser diodes

Results are presented of an extended study on the degradation and recovery behavior of optical and electrical performance and on induced lattice defects of 1.3 mu m InGaAsP double channel planar buried heterostructure laser diodes with an In sub(0.76)Ga sub(0.24)As sub(0.55)P sub(0.45) multi-quantum well active region, subjected to a 1 MeV fast neutron and 1 MeV electron irradiation. The degradation of the device performance increases with increasing fluence. Two hole capture traps with near midgap energy level in the In sub(0.76)Ga sub(0.24)As sub(0.55)P sub(0.45) multi-quantum well active region are observed after a 1x10 super(16) n /cm super(2) irradiation. These deep levels are thought to be associated with a Ga vacancy. The decrease of optical power is related to the induced lattice defects, leading to a reduction of the non-radiative recombination lifetime and of the carrier mobility due to scattering. The difference in radiation damage between 1 MeV fast neutrons and 1 MeV electrons is discussed taking into account the non-ionizing energy loss (NIEL). The radiation source dependence of performance degradation is attributed to the difference of mass and the probability of nuclear collision for the formation of lattice defects. The decreased optical power recovers by thermal annealing, and the recovery increases with increasing annealing temperature. The optical power recovers by 45% for 1 MeV neutron irradiation with a fluence of 1x10 super(15) n/cm super(2) after a 300 degree C annealing.