Electric-Field Gradients at 181Ta impurities in Sc2O3 semiconductor

D. RICHARD; E.L. MUÑOZ; L.A. ERRICO; P.D. EVERSHEIM; M. RENTERÍA

La Plata

Conferencia; HK 2010; 2011

Alexander von Humboldt Stiftung, UNLP

In this work we present a combined >ab initio and experimental study of 181Ta-doped Sc2O3 semiconductor. An extrapolation to 0 K of the experimental electric-field gradient (EFG) results obtained by Perturbed Angular Correlations (PAC) as a function of temperature suggested a reinterpretation of the charge state of the impurity in this semiconductor. The experimental temperature dependence of the EFGs at 181Ta probes located at defect-free cation sites C and D of the Sc2O3 was determined in the range 373 K - 1173 K. The theoretical calculations were performed at diluted Ta impurities located at both cationic sites, using the Full-Potential Augmented PlaneWave plus Local Orbital (FP-APW+lo) method in the framework of the Density Functional Theory (DFT), with a impurity dilution of 1:32. The structural atomic relaxations and the EFGs were studied for different charge states of the cell in order to simulate different ionization states of the double donor Ta impurity (with a neutral cell, and removing 1 or 2 electrons from the cell). These APW+lo results were found to be in excellent agreement with the experimental values.