Ab initio and experimental study of Ta-doped In2O3 semiconductor

E. L. MUÑOZ; L. A. ERRICO; G. N. DARRIBA; A. G. BIBILONI; P. D. EVERSHEIM; M. RENTERÍA

Buenos Aires, Argentina

Workshop; At the Frontiers of Condensed Matter III 2006; 2006

Ab-initio calculations based in the Density Functional Theory have shown to be appropriate for the correct description of the structural and electronic properties of oxides semiconductors doped with diluted metallic impurities. Therefore these calculations are a powerful tool and they can suggest us if is necessary to revise or to repeat an old experiment, which was analyzed without the help of these.  In this work we present a theoretical and experimental study of the  semiconductor In2O3, implanted whit (181Hf®181Ta) ions, in the ISKP of Bonn, Germany. We present results of PAC experiments in polycristals of  In2O3:Ta sesquioxide, determining the magnitude and symmetry of the EFG. The measurements was carried out at room temperature, after the annealings  (1 h at 673K, 1 h at 1073K, 6 hs at 1273K, and 1 h at 1373K), obtaining finally two interactions, assigned to substitutional probes located  in the sites C and D of cation free of defects, with the relation fC/fD=3. These results were compared with those of previous experiments, in samples prepared chemically and in implanted films, and were necessary four interactions to reproduce the experimental data, and the fractions of the probes in the places C and D were found invested.  Calculations of the electronic structures and of the EFG was carried out in the system under study, whit a impurity dilution of 1:12, with the WIEN97 implementation of the FP-LAPW method. The calculations was carried out for diverse charge states of the impurities, and compared whit PCM calculations and experimental results. Of the excellent agreement between the new experimental results and the FP-LAPW predictions could be determined the state not ionize of the impurity, and to conclude that was erroneous the assignment of the hyperfine interactions in the old experiments.