DEGRADATION MECHANISM OF GAAS ALGAAS QUANTUM-WELL LASER (VOL 26, PG 985, 1992)/

The results are reported of an investigation of the processes of degra dation in laser GaAs/AlGaAs double heterostructures with separate conf inement and a quantum well, grown by the MOSVD hydride epitaxy method. The investigation was carried out by recording the capacitance-voltag e characteristics and applying the DLTS method. Two types of laser str ucture were investigated: I) with a p-n junction located near p-Al0.5G a0.5As/n-Al0.3Ga0.7As interface and with a quantum well outside the sp ace charge region at zero reverse bias voltage (V0 = 0); II) with a qu antum well located inside the space charge region when V0 = 0. The mai n mechanism resulting in degradation of type I and II structures was f ound to be recombination-enhanced dislocation climb associated with th e absorption of point defects located at the heterojunction. In the ty pe I structures the process of dislocation climb was accompanied by ge neration of As(Ga) and V(Ga) defects, whereas in the II structure only the V(Ga) vacancies were formed. The dislocation climb in type II str uctures was observed from the p-type emitter side to the n-type wavegu ide and it was accompanied by generation of ME5 defects whose concentr ation decreased in the course of motion of dislocations. The dislocati on climb and generation of deep levels occurred also in the quantum we ll. In type I structures the dislocation climb occurred from the n- an d from the p-type emitter sides, which in final analysis resulted in l aser degradation.