Nanoscale amorphous interfaces in phase-change memory materials: structure, properties and design

Abstract

Phase-change memory (PCM) is one of the emerging technologies for the next generation of electric and optical memories. In a typical PCM device, a nanoscale amorphous interface can usually be observed. These nano amorphous interfaces are crucial because they could affect the phase transition characteristics of PCM materials, especially when the PCM devices are scaling down. In this work, according to results of our previous first-principles calculations and transmission electron microscope characterizations, we revisit the effects of three typical nano amorphous interfaces of PCM materials between different phases. We conclude that the bonding network and electronic features of the PCM material in these interfaces will be changed significantly depending on the material next to it. Different types of interface could either enhance the stability of amorphous (i.e. amorphous Si/amorphous Sb2Te3 interface) and metastable crystalline phases (i.e. amorphous GeTe/cubic Sb2Te3 interface) or promote crystallization (i.e. amorphous and crystalline Ge2Sb2Te5 interface) of the PCM materials. Therefore, a nano amorphous interface can be used to control the performance of PCM devices, such as data retention ability and crystallization speed. The present work also offers a feasible way to design novel nanoscale PCM materials based on the interface effects.