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DF: Fachverband Dielektrische Festkörper

DF 6: Glass II (joint session with DY)

DF 6.5: Talk

Tuesday, March 27, 2007, 15:50–16:10, H23

Thickness-dependence of dc-conductivity in Li₂O−B₂O₃ Glasses — Mohammad Reza Shoar Abouzari, Frank Berkemeier, and •Guido Schmitz — Institut für Materialphysik, Universität Münster, Wilhelm-Klemm Str. 10, D-48149 Münster

Thin films of (x)Li₂O · (1−x) B₂O₃ glasses with different concentrations of Li₂O, 0.15<x<0.35, are prepared by ion-beam sputtering.The thickness of glass films vary from 1400 nm down to 7 nm. Thin metallic films of Al Li on each sides of glass film serving as metallic electrodes. To determine dc-conductivity of glass layers we used impedance spectroscopy at different temperatures. Considering the system of glass layer and electrodes as two parallel (R+CPE) circuits, the measured data are described by Nyquist diagrams and the specific dc-conductivities of the glass layers are determined. It is observed that the specific dc-conductivity depend significantly on the layer thickness. For x = 0.2, the specific dc-conductivity of layers with a thickness between 700 nm and 100 nm is constant, while it increases monotonously for thinner layers with a thickness of 100 nm down to 7 nm with decreasing of the thickness. The increase of dc-conductivity amounts to three orders of magnitude. The obtained result for x = 0.15 shows the thickness dependency of the dc-conductivity up to 300 nm. It seems that this peculiar behaviour of the glass films stems from finite size effects disappears with increasing of layer thickness.