Electric-field gradient characterization at 181Ta impurities in sapphire single crystals

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

PHYSICA STATUS SOLIDI B-BASIC RESEARCH

WILEY-VCH Verlag GmbH & Co. KGaA

Lugar: Weinheim (Alemania); Año: 2005 vol. 242 p. 1928 - 1932

0370-1972

We report Perturbed-Angular-Correlation (PAC) experiments on corundum Al2O3 single crystals implanted with 181 Hf/181Ta ions at the ISKP at Bonn and measured at La Plata with high efficiency and time-resolution.The magnitude, asymmetry, and orientation (with respect to the crystalline axes) of the electric-field gradient (EFG) tensor were determined measuring the spin-rotation curves as a function of different orientations of the single crystals relative to the detector system. These results are analyzed in the framework of point-charge model and ab initio Full-Potential Linearized-Augmented Plane Wave calculations, and compared with EFG results coming from PAC experiments with 111In/111Cd impurities. This combined study enables the determination of lattice relaxations induced by the presence of the impurity and the state of charge of a deep impurity donor level in the band gap of the semiconductor.