Impact of a defect trapping layer on the reliability of 1.3 μm quantum dot laser diodes grown on silicon

In this paper, we studied the impact of a defect trapping layer on the degradation kinetics of 1.3 μm quantum dot laser diodes (QD LDs) for silicon photonics (SiPh). The purpose of the analysis is to prove how the inclusion of trapping layers (TLs) for misfit dislocations can improve the performance and reliability of QD LDs. To this aim we stressed two kinds of devices, that only differ from the inclusion of TLs. By submitting the samples to current step-stress, we tested the devices from mild to highly accelerated conditions. Our results demonstrate that a) the addition of TLs shifts the roll-off of the optical characteristics to higher current densities; b) in devices with TLs, excited state (ES) emission is reached at higher current densities, compared to standard devices; c) in terms of reliability, the addition of TLs results in a slower degradation of the threshold current, to a lower concentration of misfit dislocations in the active region; d) degradation is ascribed to the lowering of the injection efficiency, driven by the escape of carriers out of the active region, which causes an increase in the concentration of non-radiative recombination centers.