Degradation of active region in InGaAsP/InP buried heterostructure lasers

In InGaAsP/InP buried heterostructure lasers, a failure mode connected to the active region, not to the burying region, is observed. The degradation is related to a decrease in the carrier lifetime or a decrease in nonradiative lifetime due to degradations at the edges of the active region. Practically, the bad devices may be screened out by the hard screening method, however, the failure mode could determine the reliability of the devices under high-temperature or high-power operation, so care should be taken during forming the mesa and a regrowth of the burying layer.