Composition dependent electrical switching in GexSe35−xTe65(18≤x≤25) glasses–the influence of network rigidity and thermal properties

Electrical switching investigations and supportive thermal studies have been undertaken on semiconducting chalcogenide GexSe35−xTe65 (18≤x≤2518≤x≤25) glasses prepared in bulk form. An interesting composition dependent change (memory to threshold) has been observed in the switching behavior of these glasses across the stiffness/rigidity percolation threshold (RPT) at x=20x=20 (〈r〉=2.40〈r〉=2.40). Also, the rigid GexSe35−xTe65 glasses are found to retain the threshold behavior for hundreds of switching cycles. Further, the switching voltage of GexSe35−xTe65 glasses has been found to exhibit an abrupt increase at the RPT.Alternating Differential Scanning Calorimetric studies indicate that the GexSe35−xTe65 glasses with higher tellurium concentrations exhibit two crystallization exotherms, which coalesce at the composition x=20.5x=20.5 (average coordination 〈r〉=2.41〈r〉=2.41), which also marks the beginning of melting endotherms. The relatively low crystallization temperature (Tc1)(Tc1), along with the floppy structural network aids easy phase change in GexSe35−xTe65 glasses with x<20x<20, causing them to exhibit memory switching. The moderately higher crystallization temperature (300–330 ∘C) and the stabilizing influence of network connectivity & rigidity are plausibly responsible for the threshold behavior seen in the rigid GexSe35−xTe65 glasses.