1,040 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
Suppression of threading defects formation during Sb-assisted metamorphic buffer growth in InAs/InGaAs/InP structure
A virtual substrate for high quality InAs epitaxial layer has been attained
via metalorganic vapor-phase epitaxy growth of Sb-assisted InxGa1-xAs
metamorphic buffers, following a convex compositional continuous gradient of
the In content from x = 53 % to 100 %. The use of trimethylantimony (or its
decomposition products) as a surfactant has been found to crucially enable the
control over the defect formation during the relaxation process. Moreover, an
investigation of the wafer offcut-dependence of the defect formation and
surface morphology has enabled the achievement of a reliably uniform growth on
crystals with offcut towards the [111]B direction
Luttinger liquid behavior in weakly disordered quantum wires
We have measured the temperature dependence of the conductance in long
V-groove quantum wires (QWRs) fabricated in GaAs/AlGaAs heterostructures. Our
data is consistent with recent theories developed within the framework of the
Luttinger liquid model, in the limit of weakly disordered wires. We show that
for the relatively small amount of disorder in our QWRs, the value of the
interaction parameter g is g=0.66, which is the expected value for GaAs.
However, samples with a higher level of disorder show conductance with stronger
temperature dependence, which does not allow their treatment in the framework
of perturbation theory. Trying to fit such data with perturbation-theory models
leads inevitably to wrong (lower) values of g.Comment: 4 pages, 4 figure
Semiconductor nanostructures engineering: Pyramidal quantum dots
Pyramidal quantum dots (QDs) grown in inverted recesses have demonstrated
over the years an extraordinary uniformity, high spectral purity and strong
design versatility. We discuss recent results, also in view of the
Stranski-Krastanow competition and give evidence for strong perspectives in
quantum information applications for this system. We examine the possibility of
generating entangled and indistinguishable photons, together with the need for
the implementation of a, regrettably still missing, strategy for electrical
control
AlGaAs/GaAs/AlGaAs quantum wells as a sensitive tool for the MOVPE reactor environment
We present in this work a simple Quantum Well (QW) structure consisting of
GaAs wells with AlGaAs barriers as a probe for measuring the performance of
arsine purifiers within a MetalOrganic Vapour Phase Epitaxy system. Comparisons
between two different commercially available purifiers are based on the
analysis of low temperature photoluminescence emission spectra from thick QWs,
grown on GaAs substrates misoriented slightly from (100). Neutral excitons
emitted from these structures show extremely narrow linewidths, comparable to
those which can be obtained by Molecular Beam Epitaxy in an ultra-high vacuum
environment, suggesting that purifications well below the 1ppb level are needed
to achieve high quality quantum well growth
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
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