Molecular beam epitaxy growth and characterization of AlGaN epilayers in nitrogen-rich condition on Si substrate

Abstract

In this work, we investigate the molecular beam epitaxy growth and characterization of aluminum gallium nitride (AlGaN) epilayers in nitrogen (N)-rich condition on silicon using an aluminum nitride (AlN) buffer layer on a nanowire template. It is found that the growth condition of the AlN buffer layer plays an important role on the surface morphology of the AlGaN epilayers. Under the optimized growth temperature of the AlN buffer layer, a relatively smooth AlGaN epilayer can be formed, with a root-mean-square roughness of around 1.8 nm, comparable to the typical III-nitride thin films grown in N-rich conditions by molecular beam epitaxy. The epilayer is further confirmed to be N-polar from both the reflection high-energy electron diffraction 3 × 3 reconstruction and potassium hydroxide etching experiments.