INVESTIGADORES
RENTERIA Mario
congresos y reuniones científicas
Título:
PAC and ab initio study of structural and electronic properties of 111Cd impurities in SnO2
Autor/es:
EMIILIANO LUIS MUÑOZ; GERMÁN NICOLÁS DARRIBA; A.W. CARBONARI; LEONARDO A. ERRICO; MARIO RENTERÍA
Lugar:
Villa de Leyva
Reunión:
Simposio; SLAFES 2013; 2013
Institución organizadora:
SLAFES
Resumen:
In this work, we present an experimental and ab initio study of
structural and electronic properties of SnO2 doped with diluted 111Cd
impurities, located at substitutional defect free cation sites of this
semiconductor. Experimental Electric-Field-Gradient (EFG) tensor results were
obtained using the Time-Differential g-g Perturbed-Angular-Correlations (PAC) technique. The
measurements were performed in 111In((EC)→111Cd)-diffused
SnO2 polycrystalline samples, in the 10-1100K temperature range. For
all temperatures, the PAC spectra showed well-defined hyperfine interactions.
Below 600 K, an strong damping in the PAC signal was apparent, in agreement
with the presence of dynamic hyperfine interactions associated with electronic
relaxations in the 111Cd environmentattributed to the electron
capture decay after-effects of 111In.
The ab initio
calculations were performed applying the Full-Potential Augmented Plane Wave
plus local orbitals (FP-APW+lo) method. In these calculations, we used
supercells in order to obtain an impurity dilution where the impurity does not
sense the effects produced by the presence of their images, in order to
reproduce correctly the experimental results. Since the Cd impurity is formally
a double acceptor impurity in SnO2 when it replaces a Sn atom, we
performed calculations as a function of the Cd charge state, adding until 2 e-
to the doped supercell. Based in the predicted charge state dependence of the
EFG, we could present an ab initio
scenario that allows us to interpret all observed interactions and the
phenomenon of after-effects in this
impurity-host system.