Nanoscale Phase Separation in Al_0.4-Sb_0.6 Alloy for Phase Change Memory Applications

Phase change memory (PCM) is considered an enabling technology for non-volatile multilevel data storage and neuromorphic computing. Recent advancements in PCM have highlighted the need to improve resistance drift and energy efficiency. At present, binary alloys that phase-separate upon crystallization offer a promising solution. The Al–Sb binary alloy crystallizes into a rhombohedral Sb-rich phase and a cubic AlSb phase, with the latter having a higher melting temperature that enables selective melting of the Sb-rich phase for partial RESET programming. Continuum resistance states result from a reversible alloying process, in which programming pulses modulate the granularity and aluminum content of the amorphous Sb-rich phase. $Al^{0.4}$–$Sb^{0.6}$ PCM cells, fabricated on Si-foundry templates, exhibit a high resistance contrast of up to 4000× between fully amorphous and crystalline states, along with a low resistance drift coefficient (∼0.06). The high melting point of AlSb also leads to nanoscale compositional heterogeneity, which persists in the amorphous state, suppressing structural relaxation and thus reducing resistance drift. These findings position $Al^{0.4}$–$Sb^{0.6}$ as a promising material for engineering multilevel PCM cells based on phase-separating alloys.