Origin of Inversion Domains in GaN/AlN/Si(111) Heterostructures Grown by Molecular Beam Epitaxy

Abstract

Using high-resolution electron microscopy, the formation of inversion domains inside GaN layers grown by molecular beam epitaxy (MBE) on Si(111) was investigated. It was shown that when the buffer layer thickness is small (15 nm), the inversion domains form inside a nitrogen polar layer at the steps on the Si(111) surface. As the thickness of the AlN buffer layer is increased to 35 nm, the MBE GaN layer polarity switches to gallium polarity, but inversion domains still form. In this situation they originate at the GaN/AlN interface.