Vacancy-controlled model of degradation in InGaAs/AlGaAs/GaAs heterostructure lasers

A model is proposed for dark line defect (DLD) growth in semiconductor lasers by dislocation climb. The model assumes that climb occurs by the migration of randomly distributed vacancies toward existing dislocations. The effects of a strained layer on the number of vacancies and their stability are investigated. It is concluded that vacancies can act as strain relievers, thereby reducing their energy of formation. In strained-layer lasers this has the effect of reducing the driving force for DLD growth by climb but increasing the pool of vacancies available for the process to occur. These findings are offered as an explanation for the anomalous behavior of DLDs in strained-layer lasers.