Memory type switching behavior of ternary Ge20Te80-xSnx (0 x 4) chalcogenide compounds

Abstract

Chalcogenide compounds have gained huge research interest recently owing to their capability to transform from an amorphous to a crystalline phase with varying electrical properties. Such materials can be applied in building a new class of memories, such as phase-change memory and programmable metallization cells. Here we report the memory type electrical switching behavior of a ternary chalcogenide compound synthesized by doping Tin (Sn) in a germanium-telluride (Ge<inf>20</inf>Te<inf>80</inf>) host matrix, which yielded a composition of Ge<inf>20</inf>Te<inf>80-x</inf>Sn<inf>x</inf> (0 x 4). Results indicate a remarkable decrease in the threshold switching voltage (V <inf>T</inf>) from 140 to 61 V when the Sn concentration was increased stepwise, which is attributed to the domination of the metallicity factor leading to reduced amorphous network connectivity and rigidity. Variation in the threshold switching voltage (V <inf>T</inf>) was noticed even when the sample thickness and temperature were altered, confirming that the memory switching process is of thermal origin. Investigations using x-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed the formation of a crystalline channel that acts as the conduction path between the two electrodes in the switched region. Structural and morphological studies indicated that Sn metal remained as a micro inclusion in the matrix and hardly contributed to the rigid amorphous network formation in Ge<inf>20</inf>Te<inf>80-x</inf>Sn<inf>x</inf>. Memory type electrical switching observed in these ternary chalcogenide compounds synthesized herein can be explored further for the fabrication of phase-change memory devices. © 2016 IOP Publishing Ltd.