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Proceedings Paper

Size, strain and band offset engineering in GaAs(Sb)(N)-capped InAs quantum dots for 1.3 - 1.55 μm emitters
Author(s): J. M. Ulloa; M. del Moral; M. Montes; M. Bozkurt; P. M. Koenraad; A. Guzmán; A. Hierro
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Paper Abstract

The optical and structural properties of InAs/GaAs quantum dots (QD) are strongly modified through the use of a thin (~ 5 nm) GaAsSb(N) capping layer. In the case of GaAsSb-capped QDs, cross-sectional scanning tunnelling microscopy measurements show that the QD height can be controllably tuned through the Sb content up to ~ 14 % Sb. The increased QD height (together with the reduced strain) gives rise to a strong red shift and a large enhancement of the photoluminescence (PL) characteristics. This is due to improved carrier confinement and reduced sensitivity of the excitonic bandgap to QD size fluctuations within the ensemble. Moreover, the PL degradation with temperature is strongly reduced in the presence of Sb. Despite this, emission in the 1.5 μm region with these structures is only achieved for high Sb contents and a type-II band alignment that degrades the PL. Adding small amounts of N to the GaAsSb capping layer allows to progressively reduce the QD-barrier conduction band offset. This different strategy to red shift the PL allows reaching 1.5 μm with moderate Sb contents, keeping therefore a type-I alignment. Nevertheless, the PL emission is progressively degraded when the N content in the capping layer is increased.

Paper Details

Date Published: 1 March 2011
PDF: 9 pages
Proc. SPIE 7947, Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling VIII, 79470T (1 March 2011); doi: 10.1117/12.875014
Show Author Affiliations
J. M. Ulloa, Univ. Politécnica de Madrid (Spain)
M. del Moral, Univ. Politécnica de Madrid (Spain)
M. Montes, Univ. Politécnica de Madrid (Spain)
M. Bozkurt, Eindhoven Univ. of Technology (Netherlands)
P. M. Koenraad, Eindhoven Univ. of Technology (Netherlands)
A. Guzmán, Univ. Politécnica de Madrid (Spain)
A. Hierro, Univ. Politécnica de Madrid (Spain)

Published in SPIE Proceedings Vol. 7947:
Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling VIII
Kurt G. Eyink; Frank Szmulowicz; Diana L. Huffaker, Editor(s)

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