Quantum-wire spectroscopy and epitaxial-growth velocities in ${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As-InP heterostructures

We study excitons bound to quantum wires of ${\mathrm{In}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As embedded in an InP matrix, where the wires vary from 2.93 to 11.72 Å (one to four monolayers) thick and from 25 to 250 Å wide. We combine spectroscopic data from measurements of photoluminescence with variational calculations of the binding energies of excitons to the wires to deduce the wire widths and thicknesses. The widths are then related to the growth times to deduce lateral growth velocities in the vapor-levitation-epitaxial technique. Monolayer growth rates, at ∼80 Å/sec, are significantly faster than growth rates for the multilayer wires.