“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. <i>Ab initio</i> 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.