Structural and electronic properties of defective AlN/GaN hybrid nanostructures

Due to the wide range of possible applications, atomically thin two-dimensional heterostructures have attracted much attention. In this work, using first-principles calculations, we investigated the structural and electronic properties of planar AlN/GaN hybrid heterojunctions with the presence of vacancies at their interfaces. Our results reveal that a single vacancy site, produced by the removal of Aluminum or Gallium atom, yields similar electronic band structures with localized states within the bandgap. We have also observed a robust magnetic behavior. A nitrogen-vacancy, on the other hand, induces the formation of midgap states with reduced overall magnetization. We have also studied nanotubes formed by rolling up these heterojunctions. The results showed that nanotube curvature does not substantially affect the electronic and magnetic properties of their corresponding planar AlN/GaN heterojunctions. For armchair-like nanotubes, a transition from direct to indirect bandgap was observed as a consequence of changing the system geometry from 2D to a quasi-one-dimensional one.