Statistical characterization of the lifetimes of continuously operated (Al,Ga)As double-heterostructure lasers

The statistical distribution of lifetimes of routinely grown and fabricated continuously operated (Al,Ga)As double-heterostructure lasers is presented and discussed. The 90 typical devices studied were operated as lasers in a dry-nitrogen elevated-temperature ambient (70 °C) until failure. The resulting median life, τm=750 h, and mean life, 〈τ〉=1370 h, extrapolate to τm=5.7 years and 〈τ〉=10.5 years at room temperature (22 °C) using a 0.7-eV activation energy. The observed lifetimes are consistent with a model in which 17% of the lasers die prematurely as infant mortalities while 83% die by a mechanism well characterized by a lognormal distribution. The value of the standard deviation (σ=1.1) in lnτ is typical of other semiconductor devices.