Electrical switching in Si20Te80 ? xBix (0 ? x ? 3) chalcogenide glassy alloys

Abstract

Chalcogenide glasses have attained enormous research interest due to their importance in finding electronic memories. Here we report electrical switching and thermal crystallization behavior of Si<inf>20</inf>Te<inf>80 ? x</inf>Bi<inf>x</inf> (0 ? x ? 3) glasses. We observe a significant decrease in the threshold voltage (V<inf>T</inf>) and the thermal stability (?T), indicating that in Si<inf>20</inf>Te<inf>80 ? x</inf>Bi<inf>x</inf> glasses, the resistivity of the additive element Bi plays a dominant role over network connectivity/rigidity. The variation of V<inf>T</inf> with respect to thickness and temperature of the sample indicates that the memory switching observed in Si<inf>20</inf>Te<inf>80 ? x</inf>Bi<inf>x</inf> glasses is influenced by the thermally induced transitions (thermal mechanism). Scanning electron microscopy (SEM) studies on pre-switched and post switched samples reveal the morphological changes on the surface of the sample, and serve as an experimental evidence for the formation of the crystalline filament between two electrodes during switching. Furthermore, the decrease in ?T values indicates that the Si-Te glasses become de-vitrifiable more easily with the addition of Bi, influencing the decrease of V<inf>T</inf>. Structural evaluation like thermal devitrification studies and morphological changes elucidate the restricted glass formability of the studied glass system. © 2018 Elsevier B.V.