Electrical and switching properties of amorphous films based on the Ge-Se-Tl system

Electrical conductivity and I-V characteristics have been investigated as a function of thickness in the range (104.4-618.3nm) and temperature in the range (303-403K) below the glass transition T-g for thin film samples of Ge Se(9-x)Tlx (x = 2,3,4) chalcogenide glass system. The DC conductivity resul ts indicate that each composition has single activation energy DeltaE(sigma ) in the considered temperature range. The increase of Tl content in the ch alcogenide glass system leads to increase in electrical conductivity at roo m temperature sigma (RT), and decreases the activation energy DeltaE(sigma) . The observed compositional dependence of DeltaE(sigma) have been correlat ed with the increase of weak bond density and the decrease of covalent bond density in the structure of the compositions investigated with increasing Tl content. From I-V characteristic curves, it was Found that the investiga ted samples show a memory effect. The threshold voltage increases linearly with increasing film thickness while decreases exponentially with increasin g temperature. The rapid transition between the highly resistive and conduc tive states was attributed to an electrothermal model initiated from Joule heating of a current channel. (C) 2001 Elsevier Science Ltd. All rights res erved.