Enhancement of carrier lifetimes in type-II quantum dot/quantum well hybrid structures

Author(s)

Couto, Jr., O. D. D. ; de Almeida, P. T. ; dos Santos, G. E. ; Balanta, M. A. G. ; Andriolo, H. F. ; Brum, J. A. ; Brasil, M. J. S. P. ; Iikawa, F. ; Liang, B. L. ; Huffaker, D. L.

• Document type: Journal article
• Source: Journal of Applied Physics; v. 120, n. 8 AUG 28 2016.
• Web of Science Citations: 1

Abstract

We investigate optical transitions and carrier dynamics in hybrid structures containing type-I GaAs/AlGaAs quantum wells (QWs) and type-II GaSb/AlGaAs quantum dots (QDs). We show that the optical recombination of photocreated electrons confined in the QWs with holes in the QDs and wetting layer can be modified according to the QW/QD spatial separation. In particular, for low spacer thicknesses, the QW optical emission can be suppressed due to the transference of holes from the QW to the GaSb layer, favoring the optical recombination of spatially separated carriers, which can be useful for optical memory and solar cell applications. Time-resolved photoluminescence (PL) measurements reveal non-exponential recombination dynamics. We demonstrate that the PL transients can only be quantitatively described by considering both linear and quadratic terms of the carrier density in the bimolecular recombination approximation for type-II semiconductor nanostructures. We extract long exciton lifetimes from 700 ns to 5 mu s for QDs depending on the spacer layer thickness. Published by AIP Publishing. (AU)

• FAPESP's process: 14/17141-9 - Multi-User Equipment approved in grant 2012/11382-9: (iHR550) spectrometer with ICCD (SII-3LS-256-BR)-Horiba
• Grantee: Odilon Divino Damasceno Couto Júnior
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 12/11382-9 - Optical modulation of semiconductor nanostructures using surface acoustic waves
• Grantee: Odilon Divino Damasceno Couto Júnior
• Support Opportunities: Research Grants - Young Investigators Grants