Chalcogenide phase change materials: An electronic perspective

Recently, phase change materials (PCMs) have gathered attention as promising systems for a variety of emerging electronic and optoelectronic applications, including digital memory, RF switches, and switchable absorbers [1-4]. Of particular interest for electronic applications are the chalcogenide glasses, which can be repeatedly switched between two distinct, non-volatile solid phases: crystalline and amorphous, where the crystalline phase is commonly electrically conductive and the amorphous phase is generally electrically resistive. Ternary chalcogenide glasses, such as germanium antimony telluride (GeSbTe or “GST”), have been extensively examined for applications in PCM-based nonvolatile memory [5, 6]. More recently, the binary chalcogenide germanium telluride (GeTe) has gained attention for applications in RF switching due to its very low resistance in the crystalline state, relatively high amorphous-to crystalline resistance ratio (which has been found to be up to 107 in thin films), and excellent RF performance (e.g., bandwidth > 10 THz, TOI > 65 dBm) [3]. Despite significant research efforts, our understanding of electronic transport in these materials, principally in relation to RF operation and behavior, remains limited. In this presentation, we will discuss recent work at the US Naval Research Laboratory targeted at better understanding the electronic behavior of chalcogenide-based PCM devices, particularly under high-field and variable temperature conditions, with a view towards advancing the field of PCM-based reconfigurable electronics.