Experimental and ab initio study of Ta-doped ZnO semiconductor

E. L. MUÑOZ; D. RICHARD; P. D. EVERSHEIM; M. RENTERÍA

CERN, Ginebra, Suiza.

Conferencia; HFI/NQI2010, 15th International Conference on Hyperfine Interactions & 19th International Symposium on Nuclear Quadrupole Interaction; 2010

Comite organizador de la reunión

In the last  years, ab initio calculations performed in the framework of the Density Functional Theory (DFT) have been successfully applied to the study of doped oxide semiconductors. The Full-Potential Augmented Plane Wave plus local orbitals (FP-APW+lo) method enables to determine the Electric-Field-Gradient tensor (EFG) at impurity sites localized in cation sites of the host structure with very good precision. From an ab initio - experimental study, the electronic structure  and structural relaxations produced by the inclusion of the Perturbed Angular Correlation (PAC)  tracers in the host system can be determined [1,2,3] . In this work, we present PAC results in  polycrystalline ZnO semiconductor implanted with (181Hfà)181Ta probes. The FP-APW+lo calculations in Ta-doped ZnO were carried out using the supercell method and varying self-consistently the charge state of the impurity. Ta is a triple donor impurity with respect  to Zn2+ in ZnO and thus it can loose 1, 2 o 3 donor electrons under certain circumstances. The comparison between the experimental EFG results and our  ab initio predictions suggests that the Ta impurity may be in a completely ionized charge state, i.e., with the 3 donor electrons removed from the impurity. References [1] Anisotropic Relaxations Introduced by Cd Impurities in Rutile TiO2: First-Principles Calculations and Experimental Support                        L.A. Errico, G. Fabricius, M. Rentería, P. de la Presa, and M. Forker. Physical Review Letters 89, 55503 (2002). [2] Metal Impurities in an Oxide: Ab Initio Study of Electronic and Structural Properties of Cd in Rutile TiO2 L.A. Errico, G. Fabricius, and M. Rentería. Physical Review B 67, 144104 (2003). [3] Metal Impurities in an Oxide: Ab Initio Study of Electronic and Structural Properties of Cd in Rutile TiO2 G. N. Darriba, L. A. Errico, P. D. Eversheim, G. Fabricius, and M. Rentería. Physical Review B 79, 115213 (2009).