Self-organization of GaN/Al0.18Ga0.82N multi-layer nano-columns on (0 0 0 1) Al2O3 by RF molecular beam epitaxy for fabricating GaN quantum disks

Abstract

GaN nanostructures (GaN nano-column) were grown on (0001) Al2O3 by RF-radical source molecular beam epitaxy (RF-MBE) through a self-organization process. An averaged diameter of the GaN nano-column was minimized to 40–45nm by optimizing a Ga cell temperature under a fixed nitrogen supply. The self-organization process of the GaN nano-column was applied for the fabrication of the GaN/Al0.18Ga0.82N multi-quantum disk (MQD). The GaN nano-column with an averaged diameter of 46nm was fabricated, in which the 10 paired GaN(6nm)/Al0.18Ga0.82N(9nm) multi-layer structure was built in to form quantum disks. The blue shift in a photoluminescence (PL) peak wavelength at room temperature was observed for the MQD sample, probably due to the quantum-size effect.