27 research outputs found
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
Indium segregation during III-V quantum wire and quantum dot formation on patterned substrates
We report a model for metalorganic vapor-phase epitaxy on non-planar
substrates, specifically V-grooves and pyramidal recesses, which we apply to
the growth of InGaAs nanostructures. This model, based on a set of coupled
reaction-diffusion equations, one for each facet in the system, accounts for
the facet-dependence of all kinetic processes (e.g., precursor decomposition,
adatom diffusion, and adatom lifetimes) and has been previously applied to
account for the temperature, concentration, and temporal-dependence of AlGaAs
nanostructures on GaAs (111)B surfaces with V-grooves and pyramidal recesses.
In the present study, the growth of InGaAs quantum wires at
the bottom of V-grooves is used to determine a set of optimized kinetic
parameters. Based on these parameters, we have modeled the growth of
InGaAs nanostructures formed in pyramidal site-controlled
quantum-dot systems, successfully producing a qualitative explanation for the
temperature-dependence of their optical properties, which have been reported in
previous studies. Finally, we present scanning electron and cross-sectional
atomic force microscopy images which show previously unreported facetting at
the bottom of the pyramidal recesses that allow quantum dot formation.Comment: 9 pages, 8 figure