Polarization and Excitation Dependence of Photoluminescence of InAs Quantum Wires and Dots Grown on GaAs(631)

Abstract

We studied the optical properties of self-assembled InAs nanostructures grown by molecular beam epitaxy on GaAs substrates with (631) crystallographic orientation by photoluminescence (PL) spectroscopy. The growth of InAs proceeded on GaAs(631) buffer layers conformed by corrugated surfaces with a high degree of lateral periodicity (uniformly spaced nano grooves). The grooved surface is sustained even after the growth of InAs with thicknesses below 2 monolayers (ML), indicating the formation of InAs quantum wires. The one-dimensional confinement is corroborated by PL polarized along the [113] and [8,19,9] orthogonal directions. The calculated polarization degree, Πd, was 0.13 and 0.125 for InAs thicknesses of 1 and 1.5 ML, respectively. As the InAs thickness is increased, the InAs film reaches the critical thickness and quantum dots aligned along the grooved surface are formed, as observed by atomic force microscopy. Excitation-power-dependent luminescence is observed to a larger extent for low-energy PL lines in addition to a blue shift related to the band-filling effect.