Accelerated aging and a uniform mode of degradation in (Al,Ga)As double-heterostructure lasers

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Abstract
An investigation of certain of the degradation and accelerated aging characteristics of currently fabricated (Al,Ga)As lasers is described. Our observations of the properties of devices aged at 70 °C, both as light‐emitting diodes and as lasers, support two conclusions relevant to degradation: (1) The dominant degradation process in present devices is not lasing related in devices operated at power levels ⩽5 mW/face; (2) laser failure is strongly correlated with an approximately 50% reduction in the spontaneous light emission (at a given current below threshold) from these devices. These inferences are consistent with a spatially uniform mode of laser degradation not, for example, related to dark‐line defects. They also imply that an LED mode of laser testing could be effective in identifying and eliminating presently dominating degradation mechanisms, i.e., those limiting continuously operating laser lifetimes to median values of about five years at room temperature. A different degradation mechanism which is operative at elevated temperatures even in unbiased devices has also been identified.