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

Abstract

Abstract We report Perturbed‐Angular‐Correlation (PAC) experiments on corundum Al 2 O 3 single crystals implanted with 181 Hf/ 181 Ta 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 111 In/ 111 Cd 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. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)