First-principles study of size effects on electrical properties of AlN/GaN heterostructured nanofilms

•The electrical properties of AlN/GaN heterostructured nanofilms with various thicknesses are investigated by the first principles calculations.•Electron density of state, energy bands and electrical conductivity of AlN/GaN nanofilms are sensitive to the surface/interface properties and thickness.•The surface/interface engineering and size effects can be applied to control the electrical properties of GaN based-nanostructures.