Density-dependent carrier dynamics in a quantum dots-in-a-well heterostructure

The incorporation of semiconductor quantum dots into different heterostructures for applications in nanoscale lasing and amplification has been an active area of research in recent years. Here, we use ultrafast differential transmission spectroscopy to temporally and spectrally resolve density-dependent carrier dynamics in a quantum dots-in-a-well (DWELL) heterostructure. We observe excitation-dependent shifts of the quantum dot energy levels at low densities, while at high densities we observe an anomalous induced absorption at the quantum dot excited state that is correlated with quantum well population dynamics. These studies reveal unique Coulomb interaction-induced phenomena with important implications for DWELL-based lasers and amplifiers.