Ab Initio Study of the EFG Tensor at Cd Impurities in Sc2O3 Semiconductor

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

PHYSICA B - CONDENSED MATTER

Elsevier

Lugar: Amsterdam; Año: 2009 vol. 404 p. 2757 - 2759

0921-4526

We present an ab initio study of diluted Cd impurities localized at both cation sites of the semiconductor Sc2O3 . The electric-field-gradient  (EFG)  tensor  at  Cd  impurities  located  at  both  cationic  sites  of  the  host  structure  was  determined  from  the calculation of the electronic structure of the doped system. Calculations were performed  with the Full-Potential Augmented-Plane Wave  plus  Local  Orbitals  (APW+lo)  method  within  the  framework  of  the Density  Functional  Theory.  We  studied  the atomic structural relaxations and the perturbation of the electronic charge density induced by the impurities in the host system in a fully self-consistent way. We showed that the Cd impurity introduces an increase of 8% in the nearest oxygen neighbors bond-lengths,  changing  the  EFG   sign  for  probes  located  at  the  asymmetric  cation  site.  The  APW+lo  predictions  for  the charged state of the Cd impurity were compared with EFG  results existent in the literature, coming from Time-Differential gamma-gamma Perturbed-Angular-Correlations  experiments  performed  on  111Cd-implanted  Sc2O3   powder  samples.  From  the  excellent agreement  between  theory  and  experiment  we  can  strongly  suggest  that  the  Cd  acceptor  impurities  are  ionized  at  room temperature.  Finally,  we  showed  that  simple  calculations  like  those  performed  within  the  point-charge  model  with antishielding factors do not correctly describe the problem of a Cd impurity in Sc2O3 .