  We probe the extent to which dislocations reduce carrier lifetimes and alter
luminescence and growth morphology in InAs quantum dots (QD) grown on silicon.
These heterostructures are key ingredients to achieving a highly reliable
monolithically integrated light source on silicon necessary for photonic
integrated circuits. We find up to 20-30% shorter carrier lifetimes at
spatially resolved individual dislocations from both the QD ground and excited
states at room temperature using time-resolved cathodoluminescence
spectroscopy. These lifetimes are consistent with differences in the intensity
measured under steady-state excitation suggesting that trap-assisted
recombination limits the minority carrier lifetime, even away from
dislocations. Our techniques also reveal the dramatic growth of misfit
dislocations in these structures under carrier injection fueled by
recombination-enhanced dislocation glide and III-V/Si residual strain. Beyond
these direct effects of increased nonradiative recombination, we find the
long-range strain field of misfit dislocations deeper in the defect filter
layers employed during III-V/Si growth alter the QD growth environment and
introduce a crosshatch-like variation in the QD emission color and intensity
when the filter layer is positioned close to the QD emitter layer. Sessile
threading dislocations generate even more egregious hillock defects that also
reduce emission intensities by altering layer thicknesses, as measured by
transmission electron microscopy and atom probe tomography. Our work presents a
more complete picture of the impacts of dislocations relevant for the
development of light sources for scalable silicon photonic integrated circuits.
