A first-principles model for electron-capture ``after-effects´´ in 111 Cd:In2O3

MARIO RENTERÍA; LEONARDO A. ERRICO; EMILIANO L. MUÑOZ; ANIBAL G. BIBILONI

CAC (CNEA), Buenos Aires

Congreso; "At the Frontiers of Condensed Matter Physics III"; 2006

CAC (CNEA) y Depto. de Física (UBA), Argentina

The temperature dependence of the electric- field gradient (EFG) tensor at 111Cd impuritysites in oxides with the bixbyite structure has been intensively studied by means of the PACtechnique in the last twenty years. In these systems two reversible behaviors have beenobserved apparently depending if the cation has closed electronic shells (such as in Sc, In,and Y) or if it has incomplete shells as in the case of the rare earths: time-dependent(“dynamic”) hyperfine interactions and static interactions variable with temperature werefound, respectively. In2O3 doped with 111In (which decay to 111Cd by EC) is theprototype of the first behaviour. In this work we report DFT electronic structurecalculations at Cd impurities located at both cationic sites C and D of the In2O3semiconductor, performed with the FP-LAPW method with a dilution of 1:32. We studiedthe EFG at both cationic sites for different charge states of the impurities, and these resultswere found to be in excellent agreement with the experimental values. A model based inchanges of the occupation of impurity gap energy levels localized near the top of thevalence band is proposed to described the origin of the experimentally observed dynamicinteractions in this impurity- host system.