Role of deep levels in SCH SQW laser degradation manufactured with GaAs/AlGaAs by MBE technique

Deep levels in separate confinement heterostructure single quantum well GaAs/AlGaAs laser diode structures grown by molecular beam epitaxy were investigated by means of dep level transient spectroscopy. Lasers were divided into two groups dependently on the results obtained in accelerated aging tests. The first type of lasers showed stable operation during 3000 h. Contrary, lasers in the second group demonstrated poor aging behaviours. DX centers were dominant defects in the all structures studied. Additionally, The DLTS spectra have revealed the presence of the other defects. In lasers which shower rapid degradation the deep trap with thermal activation energy equal to ΔE=0.63 eV was observed in much higher concentration comparing with the concentration of the trap in reference samples. This trap has the emission characteristics essentially similar to that previously referred to as ME6. On the basis of the similarity it was identified as a complex VGa-O. As a result of its recombination properties the influence of the defect on laser parameters was found. However, a conclusion as to what extent the recombination is responsible for laser degradation has not been obtained. (author)