Progressive amorphization of GeSbTe phase-change material under electron beam irradiation

TL;DR

This study demonstrates a progressive amorphization process in GeSb2Te4 phase-change material under electron beam irradiation, revealing potential for emulating neuronal dynamics in memory devices.

Contribution

It introduces a novel in situ TEM method to observe gradual amorphization in GeSb2Te4 without melting, highlighting new mechanisms for PCM-based neuromorphic applications.

Findings

Progressive amorphization observed under electron beam

No melting occurs during the process

Potential for emulating neuronal dynamics

Abstract

Fast and reversible phase transitions in chalcogenide phase-change materials (PCMs), in particular, Ge-Sb-Te compounds, are not only of fundamental interests, but also make PCMs based random access memory (PRAM) a leading candidate for non-volatile memory and neuromorphic computing devices. To RESET the memory cell, crystalline Ge-Sb-Te has to undergo phase transitions firstly to a liquid state and then to an amorphous state, corresponding to an abrupt change in electrical resistance. In this work, we demonstrate a progressive amorphization process in GeSb2Te4 thin films under electron beam irradiation on transmission electron microscope (TEM). Melting is shown to be completely absent by the in situ TEM experiments. The progressive amorphization process resembles closely the cumulative crystallization process that accompanies a continuous change in electrical resistance. Our work suggests that if displacement forces can be implemented properly, it should be possible to emulate symmetric neuronal dynamics by using PCMs.