Optimized growth conditions for the epitaxial nucleation of β-GaN on GaAs(001) by molecular beam epitaxy

Abstract

Ultrathin (5–7 monolayers) nucleation layers of GaN are deposited on (2×4)-GaAs(001) by plasma-assisted molecular beam epitaxy. Reflection high-energy electron diffraction applied in situ reveals these layers to be epitaxial β-GaN. Transmission electron microscopy confirms this result and reveals in addition that the layers are highly connected and have an atomically abrupt interface to the GaAs substrate. The rms roughness of these layers, as measured by atomic force microscopy, is as low as 1.4 Å.