Origin of the Diffusion-Related Optical Degradation of 1.3 μm Inas QD-LDs Epitaxially Grown on Silicon Substrate

This paper investigates the origin of the diffusion process responsible for the optical degradation of InAs quantum dot (QD) laser diodes epitaxially grown on silicon. By means of a series of constant-current stress experiments carried out at different temperatures, we were able to quantitatively evaluate the temperature acceleration of the degradation process. In addition, the presence of temperature thresholds above which the degradation rate drastically increases was ascribed to the onset of a recombination-enhanced degradation process, which is favored at high temperatures. Finally, the comparison of the experimentally determined diffusion coefficients with prior scientific reports suggests that degradation is related to the recombination-enhanced diffusion of Be, used here as p-type dopant, or of the lattice defects limiting Be diffusion. The original results of this work provide new insight on the microscopic origin of the gradual optical degradation of quantum-dot lasers, which will find wide application in silicon photonics.