Fig. 1: Ge–Sb–Te ternary diagram.
From: Ab initio molecular dynamics and materials design for embedded phase-change memory
Crystallization temperatures Tx as a function of composition in the Ge–Sb–Te ternary phase diagram. This overview figure is drawn with data from refs 30,34,35,36, where these values were experimentally determined using as-deposited thin films. Two dashed lines are shown, including the pseudo-binary line (black) between Sb2Te3 and GeTe, and the tie-line (red) connecting Ge2Sb1Te2 and Ge. GST alloys approaching the Sb2Te3 endpoint (blue arrow) are most suitable for memory-oriented applications with high switching speed or for neuro-inspired computing with low resistance drift, while those approaching Ge-rich regions (red arrow) are better suited for storage-oriented applications that primarily require high amorphous-phase stability. Our ab initio simulations indicate an optimal compositional range, as marked by the green dashed line, for high-performance embedded phase-change memories.
