Quasiparticle calculations of band offsets at AlN–GaN interfaces

A first-principle quasiparticle theory in the GW approximation is used to compute valence and conduction band offsets, VBO and CBO, respectively, for hexagonal and cubic AlN–GaN interfaces. We find type I band offsets that depend on the in-plane lattice constant of the heterostructure, ranging from VBO=1.3 eV and CBO=1.5 eV for the in-plane lattice constant of a 6H–SiC (0001) substrate to VBO=0.8 eV and CBO=1.8 eV for the in-plane lattice constant of a GaN (0001) substrate. This sensitivity may explain the range of experimental results for systems whose in-plane lattice constants could not be directly measured.