Experimental evidence for non-purely electric field-induced threshold switching and modified thermal-assisted model in GeTe phase change material

Abstract

In this paper, we present a multiple layer device for investigating the impact of electric field on the conductance switching of GeTe phase change material excluding the contribution from Joule heat. The device includes a dielectric layer with excellent current-blocking which can result in a large electric field generated in the amorphous GeTe film and almost no current. With the generated electric field far beyond its threshold value for the conductance switching, our experimental data indicate that the conductance switching has not happened in the GeTe film. This indicates that the ovonic threshold switching (OTS) could not be induced by the purely electric field in amorphous chalcogenide film. Meanwhile, a modified thermal-assist model based on the Poole-Frenkel (PF) mechanism has been proposed to verify the thermal assistance is indispensable in the OTS process. And the modified model is well applied on the GeTe devices with different scales, which further supports the current experimental conclusion. This contributes to the further study of the OTS mechanism and application of the phase-change memory (PCM).