RF-MBE growth and orientation control of GaN on epitaxial graphene

Abstract GaN is proven as the most important modern semiconductor with many potential applications. Although GaN growth is matured enough, unfortunately, it is still very difficult to obtain this material with the same quality as the Si crystal, either in heteroepitaxy or homoepitaxy. GaN has recently been proposed to grow on two-dimensional (2D) layered material. This paper reports the van der Waals epitaxy (vdWE) and orientation control of GaN on epitaxial graphene (EG) by means of RF-MBE. A single crystalline GaN with a smooth surface on the EG is successfully obtained. It is found that the incorporation of an AlN intermediate layer on the EG surface significantly improves the GaN on EG. The AlN/EG structure can control the a-axis orientation of the nitride growth layer and improve the epitaxial layer quality. The GaN layers fabricated on the AlN/EG structure are also found to be free from interfacial stress. The quality of the GaN layer obtained on the AlN/EG structure is comparable to that of the GaN layer on the sapphire substrate. This research paves the way for the expansion of high-quality GaN on EG.