Optical Properties of GaN/AlN(0001) Quantum Dots Grown by Plasma-Assisted Molecular Beam Epitaxy

Abstract

We have investigated the Ga-flux dependence of growth morphology and optical properties of GaN quantum dots (QDs) in AlN(0001). The QDs formed either by Stranski–Krastanov (S–K) or autosurfactant modified S–K growth depending on the incident Ga-flux during rf-plasma assisted molecular beam epitaxy. We correlated reflection high-energy electron diffraction specular intensity transients to the QD dimensions measured by atomic force microscopy. Single QD layers with growth mode dependant size, density, and wetting layer thickness were characterized by room temperature photoluminescence (PL) with a pulsed 193 nm excitation source. We used a self-consistent one-dimensional Schrödinger–Poisson calculation to identify the contribution of wetting layer quantum wells (1–4 monolayer GaN) and QDs in the PL spectra.