Crystallography of epitaxial growth of wurtzite-type thin films on sapphire substrates

Abstract

In this article, we present a crystallographic model to describe the epitaxial growth of wurtzite-type thin films such as gallium nitride (GaN) on different orientations of sapphire (Al2O3) substrates. Through this model, we demonstrate the thin films grown on (00⋅1)Al2O3 have a better epilayer-substrate interface quality than those grown on (01⋅2)Al2O3. We also show the epilayer grown on (00⋅1)Al2O3 are gallium-terminated, and both (00⋅1) and (01⋅2) surfaces of sapphire crystals are oxygen-terminated.