Electronic and structural characterization of barrier-type amorphous aluminium oxide.
Evangelisti, F., Stiefel, M., Guseva, O., Nia, Raheleh P., Hauert, Roland., Hack, E., Jeurgens, L. P.H., Ambrosio, F., Pasquarello, A., Schmutz, P., Cancellieri, C.
Electrochimica Acta, 224, 503-516., 2017
The full dielectric response of the oxides, including both the lattice and electronic components, has been accessed by electrochemical impedance spectroscopy and Auger analysis. The lattice contribution of the dielectric constant is found to be strongly affected by the growth voltage, as a clear increase in the lattice component of the dielectric constant is observed, reaching values close to those of bulk crystalline Al2O3 structures. At variance, the electronic contribution is only slightly affected. The results have been compared to dielectric constants calculated for atomistic amorphous models within the framework of density functional theory.
It is shown that amorphous Al2O3 models of higher density lead to dielectric constants that could explain the trend observed in theseries of barrier-type anodic oxides prepared in this work.