481 research outputs found
A site-controlled quantum dot system offering both high uniformity and spectral purity
In this paper we report on the optical properties of site controlled InGaAs
dots with GaAs barriers grown in pyramidal recesses by metalorganic vapour
phase epitaxy. The inhomogeneous broadening of excitonic emission from an
ensemble of quantum dots is found to be unusually narrow, with a standard
deviation of 1.19 meV, and spectral purity of emission lines from individual
dots is found to be very high (18-30 ueV), in contrast with other
site-controlled systems.Comment: 12 pages, 3 figure
Impact of Nitrogen incorporation on pseudomorphic site-controlled quantum dots grown by Metalorganic Vapour Phase Epitaxy
We report on some surprising optical properties of diluted nitride
InGaAs_(1-y)N_y /GaAs (y<<1) pyramidal site-controlled quantum dots, grown by
metalorganic vapor phase epitaxy on patterned GaAs (111)B substrates.
Microphotoluminescence characterizations showed antibinding exciton/ biexciton
behavior, a spread of exciton lifetimes in an otherwise very uniform sample,
with unexpected long neutral exciton lifetimes (up to 7 ns) and a nearly zero
fine structure splitting on a majority of dots
Wettability and "petal effect" of GaAs native oxides
We discuss unreported transitions of oxidized GaAs surfaces between
(super)hydrophilic and hydrophobic states when stored in ambient conditions.
Contact angles higher than 90deg and high adhesive force were observed for
several air-aged epitaxial samples grown under different conditions as well as
on epi-ready wafers. Regardless of the morphologies of the surface,
superhydrophilicity of oxygen-plasma treated samples was observed, an effect
disappearing with storage time. Reproducible hydrophobicity was likewise
observed, as expected, after standard HCl surface etching. The relation between
surface oxides and hydrophobic/hydrophilic behavior is discussed
Why Did Belgium Pay Leopold’s Bonds?
The longitudinal-optical (LO)-phonon coupling is experimentally examined by the optical decay of various charged and neutral exciton species in single quantum dots, and the related Huang-Rhys parameters are extracted. A positive trion exhibits significantly weaker LO-phonon replicas in the photoluminescence spectrum than the neutral and negatively charged species. Model computations show that the strength of the replicas is determined by the Coulomb interactions between electrons and holes, which modify the localization of the envelope wave functions and the net charge distribution.Original Publication: Daniel Dufåker, Fredrik Karlsson, V Dimastrodonato, L O Mereni, Bo Sernelius, Per-Olof Holtz and E Pelucchi, Phonon replicas of charged and neutral exciton complexes in single quantum dots, 2010, PHYSICAL REVIEW B, (82), 20, 205421. http://dx.doi.org/10.1103/PhysRevB.82.205421 Copyright: American Physical Society http://www.aps.org/</p
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