Impact of DoS changes on resistance drift and threshold switching in amorphous phase change materials

Abstract

Phase change materials are probably the most promising candidates to be used in the upcoming generation of memory technologies. One of the main challenges for applications is the resistance increase over time occurring in the amorphous state called resistance drift. We have studied the time and temperature dependence of resistance drift in thin films of GeTe and other phase change materials. A relationship for the time and temperature dependence of the activation energy for conduction is used to describe resistance drift. Photothermal Deflection Spectroscopy shows that the optical band gap is increasing, suggesting to be the reason for an increase of the activation energy. Furthermore, our results on various materials show that the magnitude of drift tends to be dependent on the activation energy for conduction. A similar trend is observed for the dependence of the threshold switching field on the optical band gap. © 2012 Elsevier B.V. All rights reserved.