MACROSCOPIC POLARIZATION AND BAND OFFSETS AT NITRIDE HETEROJUNCTIONS

Ab initio electronic structure studies of prototypical polar interface s of wurtzite m-V nitrides show that large uniform electric fields exi st in epitaxial nitride overlayers, due to the discontinuity across th e interface of the macroscopic polarization of the constituent materia ls. Polarization fields require a nonstandard evaluation of band offse ts and formation energies: we find a large strain-induced asymmetry of the offset [0.2 eV for AlN/GaN (0001), 0.85 eV for GaN/AlN (0001)], a nd tiny interface formation energies. [S0163-1829(98)52116-9].