IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Ab initio study of structural and electronic properties of Ta impurities in SnO2
Autor/es:
G. DARRIBA; E. MUĂ‘OZ; L. A. ERRICO; M. RENTERIA
Lugar:
Villa de Leyva
Reunión:
Conferencia; SLAFES XXI; 2013
Institución organizadora:
Universidad Nacional de Colombia
Resumen:
In this work, we present ab initio calculations of structural and electronic properties of Ta impurities, located at substitutional cation sites of the SnO2 semiconductor. The calculations were performed, in the framework of the Density Functional Theory, using the WIEN2k code implementation of the Full-Potential Augmented Plane Wave plus local orbitals (FP-APW+lo) method. The results obtained for the electric-field-gradient tensor (EFG) are here compared with experimental results obtained using the Time-Differential Perturbed-Angular-Correlations technique (TDPAC). We used 2x2x3 supercells in order to obtain the correct impurity dilution, and since Ta is a single donor impurity in SnO2, we performed the ab initio calculations for two-charge state: neutral and charged. Ta introduces an impurity level in the gap region at the bottom of the conduction band, which is partially filled in the neutral and empty in the charged charge state, respectively. Ta produces contractions in Ta-O distances, and these relaxations try to reconstruct the neighborhood of Ta-O in Ta2O5. After structural relaxations, the ab initio calculations provided almost the same EFG for both charge states, since the removed electron is not localized at the Ta atom and the final oxygen positions are similar. Finally, comparing the TDPAC results, the predicted EFG and formation energy calculations, we showed that the 181Ta impurities are located at substitutional defect ?free Sn sites in the SnO2 host lattice, being the impurity already ionized at RT.
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