High spin states of cation vacancies in GaP, GaN, AlN, BN, ZnO and BeO: A first principles study

摘要

High spin states of cation vacancies in GaP, GaN, AlN, BN, ZnO and BeO wereanalyzed by first principles calculations. The spin-polarized vacancy-inducedlevel is located in the band gap in GaP, ZnO and BeO. In the nitrides, thestronger exchange coupling forces the vacancy states to be resonant withvalence bands, forbids formation of positively charged vacancies in GaN and BN,and allows Al vacancy in p-AlN to assume the highest possible S=2 spin state.The shape of the spin density, isotropic in the zinc blende structure, has apronounced directional character in the wurtzite structure. Stability of spinpolarization of the vacancy states is determined by spin polarization energiesof anions, as well as by interatomic distances between the vacancy neighbors,and thus is given by both the lattice constant of the host and the atomicrelaxations around the vacancy. Implications for experiment are discussed.