"Stickier"-Surface Sb2Te3 Templates Enable Fast Memory Switching of Phase Change Material GeSb2Te4 with Growth-Dominated Crystallization

Ge-Sb-Te (GST)-based phase-change memory (PCM) excels in the switching performance but remains insufficient of the operating speed to replace cache memory (the fastest memory in a computer). In this work, a novel approach using Sb2Te3 templates is proposed to boost the crystallization speed of GST by five times faster. This is because such a GST/Sb2Te3 heterostructure changes the crystallizing mode of GST from the nucleation-dominated to the faster growth-dominated one, as confirmed by high-resolution transmission electron microscopy, which captures the interface-induced epitaxial growth of GST on Sb2Te3 templates in devices. Ab initio molecular dynamic simulations reveal that Sb2Te3 templates can render GST sublayers faster crystallization speed because Sb2Te3's "sticky" surface contains lots of unpaired electrons that may attract Ge atoms with less antibonding interactions. Our work not only proposes a template-assisted PCM with fast speed but also uncovers the hidden mechanism of Sb2Te3's sticky surface, which can be used for future material selection.