Defect chemical modeling of mesoscopic ion conduction in nanosized CaF2/BaF2 multilayer heterostructures

Interfacial and mesoscopic size effects in molecular beam epitaxy-grown CaF2/BaF2 heterolayers have been quantitatively analyzed on the basis of Gouy-Chapman and Mott-Schottky space-charge profiles. The linear dependence of the overall parallel conductivity on the inverse interfacial spacing found for large interfacial spacings (l > 50 nm) can be obtained from both models being in good agreement with the experimental data. An upward bending occurring for small interfacial spacings (l < 30 nm) can only be reproduced by the Mott-Schottky model based on the assumption of frozen-in impurity profiles.