Optics | Physical Sciences and Mathematics | Physics
This paper investigates the effects of Coulomb interactions on the emission dynamics of Sb-containing quantum dot (QD) systems under high excitation densities. Two different type-II confinements are studied: confined electrons with unconfined holes using InAs/GaAs QDs capped with a GaAsSb quantum well (type-IIa), and confined holes with unconfined electrons using GaSb/GaAs QDs capped with an InGaAs quantum well (type-IIb). Time-resolved photoluminescence experiments are compared with self-consistent numerical calculations using an 8-band k·p model. In both structures, we observe a significant blueshift of emission and wavelength-dependent radiative lifetimes, but with marked quantitative differences between the two systems: in the type-IIa, the blueshift is 12 meV with a change in lifetime from 1.4 ns to 2.0 ns, and in the type-IIb, the blueshift is 63 meV with lifetime change from 100 ps to 23 ns. We present a comprehensive explanation of all the important features of the experimental data in terms of Coulomb-induced changes to the carrier wave functions and confining potentials, with the separate confinement of the electrons and holes being a crucial factor.
Gradkowski, K. and Ochalski, T. J. and Pavarelli, N. and Liu, H. Y. and Tatebayashi, J. and Williams, D. P. and Mowbray, D. J. and Huyet, G. and Huffaker, D. L., Coulomb-induced emission dynamics and self-consistent calculations of type-II Sb-containing quantum dot systems, Phys. Rev. B, 85(3) 2012. 10.1103/PhysRevB.85.035432