An Initial Exploration of GaN Grown on a Ge-(111) Substrate

Abstract

Using electron microscopy techniques, two types of defect have been identified in a GaN epilayer grown directly on a Ge-(111) substrate using plasma assisted molecular beam epitaxy (PAMBE) without any intermediate buffer layers. One defect, initially observed with optical microscopy, has a triangular shape in plan-view imaging and is essentially a faceted void in the Ge extending from the interface into the substrate. Another type of defect is the formation of domains due to the misorientation of the GaN relative to the Ge substrate with a twist of +/- 4 degrees about the GaN-[0002] axis.