Enhancement of carrier lifetimes in type-II quantum dot/quantum well hybrid structures
- Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, 13083-859 Campinas, São Paulo (Brazil)
- California NanoSystems Institute, UCLA, Los Angeles, California 90095 (United States)
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 μs for QDs depending on the spacer layer thickness.
- OSTI ID:
- 22598834
- Journal Information:
- Journal of Applied Physics, Vol. 120, Issue 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM ARSENIDES
CARRIER DENSITY
CARRIER LIFETIME
ELECTRONS
GALLIUM ANTIMONIDES
GALLIUM ARSENIDES
LAYERS
PHOTOLUMINESCENCE
QUANTUM DOTS
QUANTUM WELLS
RECOMBINATION
SEMICONDUCTOR MATERIALS
THICKNESS
TIME RESOLUTION
TRANSIENTS