1,182 research outputs found
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
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
Unusual nanostructures of "lattice matched" InP on AlInAs
We show that the morphology of the initial monolayers of InP on
Al0.48In0.52As grown by metalorganic vapor-phase epitaxy does not follow the
expected layer-by-layer growth mode of lattice-matched systems, but instead
develops a number of low-dimensional structures, e.g., quantum dots and wires.
We discuss how the macroscopically strain-free heteroepitaxy might be strongly
affected by local phase separation/alloying-induced strain and that the
preferred aggregation of adatom species on the substrate surface and reduced
wettability of InP on AlInAs surfaces might be the cause of the unusual (step)
organization and morpholog
Morphological, compositional, and geometrical transients of V-groove quantum wires formed during metalorganic vapor-phase epitaxy
We present a theoretical model of the formation of self-limited (Al) GaAs quantum wires within V-grooves on GaAs(001) substrates during metalorganic vapor-phase epitaxy. We identify the facet-dependent rates of the kinetic processes responsible for the formation of the self-limiting profile, which is accompanied by Ga segregation along the axis perpendicular to the bottom of the original template, and analyze their interplay with the facet geometry in the transient regime. A reduced model is adopted for the evolution of the patterned profile, as determined by the angle between the different crystallographic planes as a function of the growth conditions. Our results provide a comprehensive phenomenological understanding of the self-ordering mechanism on patterned surfaces which can be harnessed for designing the quantum optical properties of low-dimensional systems. (C) 2013 AIP Publishing LLC
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