High field electrical switching behavior of Ge10Se90−xTlx glasses

Abstract

Electrical switching studies on bulk Ge10Se90−xTlx (15 ⩽ x ⩽ 34) glasses have been undertaken to examine the type of switching, composition and thickness dependence of switching voltages. Unlike Ge–Se–Tl thin films which exhibit memory switching, the bulk Ge10Se90−xTlx glasses are found to exhibit threshold type switching with fluctuations seen in their current–voltage (I–V) characteristics. Further, it is observed that the switching voltages (VT) of Ge10Se90−xTlx glasses decrease with the increase in the Tl concentration. An effort has been made to understand the observed composition dependence on the basis of nature of bonding of Tl atoms and a decrease in the chemical disorder with composition. In addition, the network connectivity and metallicity factors also contribute for the observed decrease in the switching voltages of Ge10Se90−xTlx glasses with Tl addition. It is also interesting to note that the composition dependence of switching voltages of Ge10Se90−xTlx glasses exhibit a small cusp around the composition x = 22, which is understood on the basis of a thermally reversing window in this system in the composition range 22 ⩽ x ⩽ 30. The thickness dependence of switching voltages has been found to provide an insight about the type of switching mechanism involved in these samples.