Composition dependent electrical switching in [formula omitted] glasses–the influence of network rigidity and thermal properties

Abstract

Electrical switching investigations and supportive thermal studies have been undertaken on semiconducting chalcogenide Ge x Se 35− x Te 65 ( 18 ≤ 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 = 20 ( 〈 r 〉 = 2.40 ). Also, the rigid Ge x Se 35− x Te 65 glasses are found to retain the threshold behavior for hundreds of switching cycles. Further, the switching voltage of Ge x Se 35− x Te 65 glasses has been found to exhibit an abrupt increase at the RPT. Alternating Differential Scanning Calorimetric studies indicate that the Ge x Se 35− x Te 65 glasses with higher tellurium concentrations exhibit two crystallization exotherms, which coalesce at the composition x = 20.5 (average coordination 〈 r 〉 = 2.41 ), which also marks the beginning of melting endotherms. The relatively low crystallization temperature ( T c 1 ) , along with the floppy structural network aids easy phase change in Ge x Se 35− x Te 65 glasses with x < 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 Ge x Se 35− x Te 65 glasses.