INFLUENCES OF DARK LINE DEFECTS ON CHARACTERISTICS OF ALGAAS/GAAS QUANTUM-WELL LASERS GROWN ON SI SUBSTRATES

We report the influences of dark line defects (DLD's) on characteristics of AlGaAs/GaAs quantum well lasers grown on Si substrates under continuous-wave aging operation. Electroluminescence topography revealed that rapid degradation of an AlGaAs/GaAs laser on Si was caused by the rapid growth of [100] DLD's. The generation of [100] DLD's causes the decrease of internal differential quantum efficiency (eta) due to the increased number of nonradiative recombination centers. It also causes decrease of the differential gain coefficient (beta) and slow increase of driving current at the initial slow degradation stage. At the subsequent rapid degradation stage, rapid increase of driving current is caused by the drastic increase of internal loss (alpha(i)) and decrease of beta due to the growth of the DLD's. It is also found that the DLD growth velocity depends more strongly on the injected current density than on the junction temperature.