GaAsSb-capped InAs quantum dots: From enlarged quantum dot height to alloy fluctuations

Journal Article · Thu Apr 15 04:00:00 EDT 2010 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.81.165305· OSTI ID:21366733

Ulloa, J M; Gargallo-Caballero, R; Moral, M del; Guzman, A; Hierro, A ^[1]; Bozkurt, M; Koenraad, P M ^[2]

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1. Institute for Systems based on Optoelectronics and Microtechnology (ISOM), Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)
2. Photonics and Semiconductor Nanophysics, Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, NL-5600 MB Eindhoven (Netherlands)

The Sb-induced changes in the optical properties of GaAsSb-capped InAs/GaAs quantum dots (QDs) are shown to be strongly correlated with structural changes. The observed redshift of the photoluminescence emission is shown to follow two different regimes. In the first regime, with Sb concentrations up to approx12%, the emission wavelength shifts up to approx1280 nm with a large enhancement of the luminescence characteristics. A structural analysis at the atomic scale by cross-sectional scanning tunneling microscopy shows that this enhancement arises from a gradual increase in QD height, which improves carrier confinement and reduces the sensitivity of the excitonic band gap to QD size fluctuations within the ensemble. The increased QD height results from the progressive suppression of QD decomposition during the capping process due to the presence of Sb atoms on the growth surface. In the second regime, with Sb concentrations above approx12%, the emission wavelength shifts up to approx1500 nm, but the luminescence characteristics progressively degrade with the Sb content. This degradation at high Sb contents occurs as a result of composition modulation in the capping layer and strain-induced Sb migration to the top of the QDs, together with a transition to a type-II band alignment.

• OSTI ID: 21366733
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 16 Vol. 81; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOY SYSTEMS
ALLOYS
ANTIMONY ALLOYS
ARSENIC ALLOYS
ARSENIC COMPOUNDS
ARSENIDES
CHEMICAL REACTIONS
DECOMPOSITION
EMISSION
FLUCTUATIONS
GALLIUM ALLOYS
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
INDIUM ARSENIDES
INDIUM COMPOUNDS
LAYERS
LUMINESCENCE
MICROSCOPY
MIGRATION
MODULATION
NANOSTRUCTURES
OPTICAL PROPERTIES
PHOTOLUMINESCENCE
PHOTON EMISSION
PHYSICAL PROPERTIES
PNICTIDES
QUANTUM DOTS
RED SHIFT
SCANNING TUNNELING MICROSCOPY
SENSITIVITY
STRAINS
SURFACES
TERNARY ALLOY SYSTEMS
VARIATIONS
WAVELENGTHS