Defect chemical modeling of mesoscopic ion conduction in nanosized $\mathrm{Ca}{\mathrm{F}}_{2}∕\mathrm{Ba}{\mathrm{F}}_{2}$ multilayer heterostructures

Defect chemical modeling of mesoscopic ion conduction in nanosized $Ca F_{2} ∕ Ba F_{2}$ multilayer heterostructures

Xiangxin Guo, Ion Matei, Janez Jamnik, Jong-Sook Lee, and Joachim Maier

Phys. Rev. B 76, 125429 – Published 24 September 2007

Abstract

Interfacial and mesoscopic size effects in molecular beam epitaxy-grown $Ca F_{2} ∕ Ba F_{2}$ 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.