Crystallization kinetics of stacked phase-change films for multi-level storage

Abstract

Good thermal stability, fast operation speed, high-level storage density, and low power consumption are increasingly required for neuro-inspired phase-change random access memory. Herein, we designed a multi-level storage phase-change film with three Sb–GeO₂ components that are stacked and separated by SiO₂ dielectric layers. The fragile-to-strong (F–S) kinetics feature, which is desirable in phase-change supercooled liquids for alleviating the contradictory relation between good thermal stability near the glass transition temperature and fast crystallization speed around the melting temperature, is revealed in some of the Sb–GeO₂ components. Moreover, we found that the introduction of stacked structures and adjacent phase-change layers can significantly weaken the F–S kinetics feature of the low thermally stable Sb–GeO₂ film but has no influence on the high thermally stable Sb–GeO₂ film. It is confirmed that the residual stresses arise from the expansion of stacked films are the origins for the influence on the crystallization kinetics. These findings open opportunities for the design of high-density storage devices with multilayer phase-change films to large-scale neuro-inspired computing.