Indium segregation during III-V quantum wire and quantum dot formation on patterned substrates

摘要

We report a model for metalorganic vapor-phase epitaxy on non-planarsubstrates, specifically V-grooves and pyramidal recesses, which we apply tothe growth of InGaAs nanostructures. This model, based on a set of coupledreaction-diffusion equations, one for each facet in the system, accounts forthe facet-dependence of all kinetic processes (e.g., precursor decomposition,adatom diffusion, and adatom lifetimes) and has been previously applied toaccount for the temperature, concentration, and temporal-dependence of AlGaAsnanostructures on GaAs (111)B surfaces with V-grooves and pyramidal recesses.In the present study, the growth of In$_{0.12}$Ga$_{0.88}$As quantum wires atthe bottom of V-grooves is used to determine a set of optimized kineticparameters. Based on these parameters, we have modeled the growth ofIn$_{0.25}$Ga$_{0.75}$As nanostructures formed in pyramidal site-controlledquantum-dot systems, successfully producing a qualitative explanation for thetemperature-dependence of their optical properties, which have been reported inprevious studies. Finally, we present scanning electron and cross-sectionalatomic force microscopy images which show previously unreported facetting atthe bottom of the pyramidal recesses that allow quantum dot formation.