Multi-cycle RHEED oscillation under nitrogen supply in alternative source supply AlN growth by rf-MBE

Abstract

An alternative source supply sequence was applied to aluminum nitride (AlN) growth by rf-plasma-assisted molecular-beam epitaxy on silicon carbide (SiC) substrates with a high-quality AlN template layer. Under a nitrogen-only source supply after aluminum source supply, multi-cycle oscillations of reflection high-energy electron diffraction (RHEED) intensity were observed, which were due to layer-by-layer growth of the AlN layer. The RHEED oscillation under nitrogen-only supply indicates that excess aluminum exists on the surface as a few-monolayer-thick wetting layer along with microdroplets. By repeating the sequence, a 105 nm thick high-quality AlN layer was coherently grown on a SiC substrate without aluminum droplets.