The effects of N vacancies on the transition metal (Cr, Mn, Fe, Co, Ni, and Cu) doped GaN were studied at the levels of the local spin density approximation (LSDA) and LSDA+U (Coulomb interaction). The calculations showed that the N vacancy favourably exists near a transition metal ion and the interaction between transition metal ion and N vacancy was insensitive to the distance when exceeding 3.3 Å. Furthermore, it was found that the existed N vacancies alter the magnetic moments of the doped GaN, where the magnetic moments increased for Cr or Mn doped GaN, and decrease for Fe, Co, Ni, or Cu doped GaN. This result could be interpreted well by the Hund’s multiplicity rules. However, it was found that the magnetic moments of doped GaN with N vacancies were insensitive to the distances between N vacancies and the doped transition metal ions. The results obtained were useful in elucidating the effects of N vacancies on the magnetic properties of the transition metal doped GaN.

Effects of Nitrogen Vacancies on Transition-Metal-Doped GaN - an ab initio Study. B.Xu, B.C.Pan: Journal of Applied Physics, 2009, 105[10], 103710