Nanoscale phase separation in Al0.4–Sb0.6 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–Sb 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–Sb as a promising material for engineering multilevel PCM cells based on phase-separating alloys.