Calculations were made of the formation energy of single vacancy in V-doped ZnO in different conditions (oxygen or zinc-rich) by first principles. Effect of an

intrinsic vacancy on the electronic density of states and magnetic moment of V-doped ZnO (Zn15VO16) with and without single vacancy was also calculated. The calculation was performed within the spin-polarized GGA approximation implemented in materials studio software. The formation energy showed that oxygen vacancy inclined to stay far from vanadium  and zinc vacancy preferred to stay at a position near V. The calculated formation energy also showed that a zinc vacancy may automatically occur but an oxygen vacancy may not appear automatically. Vanadium doping introduced spin-polarization around Fermi level. For an energy favorable vacancy, an oxygen vacancy had little effect on the electronic density of states. A zinc vacancy made the spin-polarization peaks around Fermi level broaden and decreased their magnitude. For the magnetic moment in energy favorable configurations, an oxygen vacancy had little effect on the magnetic moment; a zinc vacancy significantly decreased the magnetic moment (as high as 63.7%). Changes in magnetic moments were consistent with electronic density of states. The calculations could explain various experimental magnetic moment values. The work also provided a reference for preparing V-doped ZnO-based dilute magnetic semiconductors.

First-Principles Study of Single Intrinsic Vacancy Formation and its Effect on the Electronic Density States and Magnetic Moment of V-Doped ZnO. Wang, Q.B., Zheng, G., Chen, Q.L., Wan, M., Wang, X.C.: Physica B, 2012, 407[4], 719–23