IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
artículos
Título:
Experimental and First-Principles Theoretical Study of Structural and Electronic Properties in Tantalum-Doped In2O3 Semiconductor: Finding a Definitive Hyperfine Interaction Assignment
Autor/es:
GERMÁN NICOLÁS DARRIBA; PAUL D. EVERSHEIM; DIEGO RICHARD; EMILIANO L. MUÑOZ; LEONARDO A. ERRICO; MARIO RENTERÍA
Revista:
JOURNAL OF PHYSICAL CHEMISTRY C
Editorial:
AMER CHEMICAL SOC
Referencias:
Lugar: Washington; Año: 2016 vol. 120 p. 5640 - 5650
ISSN:
1932-7447
Resumen:
In this work we present an experimentaland theoretical study from first-principles of the structural, electronic, andhyperfine properties of Ta-doped In2O3semiconductor. The ab initioelectronic structure calculations in the Ta-diluted In2O3system enabled to obtain the structural lattice distortions and the hyperfineparameters when the Ta atom is placed at each cationic site of the bixbyite crystal structure. To thispurpose we used the Full-Potential Augmented Plane Wave plus local orbital(FP-APW+lo) method, within the Density Functional Theory. The obtained resultsindicate that the substitutional Ta probe-impurity produces strong changes onthe local structure.In addition, we performed accurateTime-Differential Perturbed gamma-gamma Angular Correlations (TDPAC) key experiments in (181Hf→)181Ta-implantedIn2O3 samples with high crystallinity, in order to obtainhigh quality measurements of the electric-fieldgradient (EFG) tensor that unraveled the controversy settled in the literatureand overcome dissimilar interpretations of previously reported  TDPAC experiments. The experiments wereperformed at room temperature in air, after each step of a series of thermal annealingtreatments in air at increasing temperatures in order to remove radiationdamage and locate the 181Hf probes at substitutional cationic sites.We succeeded toobtained two well-defined hyperfine interactions thatwere assigned to 181Ta probes located at the two defect-free inequivalentcationic sites of the In2O3 crystal structure. The EFG calculations are in excellentagreement with the results of these TDPAC measurements, and show that the EFGat the Ta site has mainly pcharacter. The accuracy of theexperiments together with the reliable and precise ab initio results allowed a definitive determination of the EFG atboth cationic sites in this system. Formation energy calculations ofdefects were needed to determine the charge state of the 181Taimpurity, which agrees with a semiconducting character for the In2O3:Tadoped system.