Improving the Reliability of InAs Quantum-Dot Laser Diodes for Silicon Photonics: the Role of Trapping Layers and Misfit-Dislocation Density

This paper investigates the role of the insertion of trapping layers, above and below the active region, in improving the reliability of 1.31 µm InAs quantum-dot laser diodes epitaxially grown on silicon substrate. The study is based on an extensive set of characterization and accelerated aging experiments carried out on two groups of quantum-dot lasers, featuring the same geometry and epitaxial structure, but differing in the presence or absence of defect trapping layers. The results of our work demonstrate that devices with trapping layers exhibit i) higher optical performance in terms of L-I characteristics, ii) longer lifetime, when aged at similar temperatures and identical current densities, and iii) similar degradation modes with respect to the devices without trapping layers. This latter point highlights the role of epitaxial structure optimization in the improvement of the lifetime of the IR optical sources for next-generation silicon photonics. The selective reduction in concentration of specific defects, misfit dislocations rather than threading dislocations in this case, can effectively improve the reliability of the devices.