Interfacial Sb Sequestration-Expulsion Enabled by Homojunction-like Layered Structures for Multifunctional Memory

Elemental antimony (Sb) enables ultrafast crystallization but suffers from poor amorphous stability. Here, we report a Sb/GaSb4 homojunction-like architecture in which chemically similar yet electronically distinct interfaces regulate phase-change behavior. Increasing interfacial density markedly elevates the crystallization temperature and enhances data retention, accompanied by delayed crystallization and preserved layered structures. We further identify an interfacial sequestration-expulsion mechanism: adjacent Sb layers suppress excess-Sb expulsion from the GaSb4 matrix, while Ga promotes Sb accommodation and thermally driven redistribution, stabilizing Sb-rich local environments. As a result, devices achieve 5 ns switching, >105 endurance cycles, and low resistance drift. Moreover, interfacial-density scaling enables linear conductance modulation, supporting both high-speed memory and neuromorphic functionality. These findings establish interface-engineered homojunction-like structures as an effective strategy to mitigate phase-change trade-offs and enable multifunctional electronics.