Creation of regular arrays of faceted AlN nanostructures via a combined top-down, bottom-up approach

The realisation of spatially-determined, uniform arrays of faceted aluminium nitride (AlN) nanostructures has had limited exploration, largely due to the fact that selective area growth of AlN via MOVPE (Metal Organic Vapour Phase Epitaxy) has not been realised. Instead, this paper reports the use of a combined top-down, bottom-up approach to realise well-faceted, highly-uniform, periodic nanotextured AlN surfaces. MOVPE regrowth is performed upon dry-etched AlN nanorods and nanoholes, and we present a study into the effect of the growth conditions on the resulting faceting and morphology. Specifically, growth temperature, V/III ratio and growth time are investigated and analysed via scanning-electron and atomic-force microscopy. The V/III ratio was found to influence the nanostructure morphology most whilst the growth temperature was found to have much less of an impact within the temperature range studied. Experiments with a longer growth time are performed to create nanostructures for potential use in applications, such as for AlGaN-based quantum-well or quantum-dot emitters.