Compositionally matched nitrogen-doped Ge₂Sb₂Te₅/Ge₂Sb₂Te₅ superlattice-like structures for phase change random access memory

A compositionally matched superlattice-like (SLL) structure comprised of Ge₂Sb₂Te₅ (GST) and nitrogen-doped GST (N-GST) was developed to achieve both low current and high endurance Phase Change Random Access Memory (PCRAM). N-GST/GST SLL PCRAM devices demonstrated ∼37% current reduction compared to single layered GST PCRAM and significantly higher write/erase endurances of ∼10⁸ compared to ∼10⁶ for GeTe/Sb₂Te₃ SLL devices. The improvements in endurance are attributed to the compositionally matched N-GST/GST material combination that lowers the diffusion gradient between the layers and the lower crystallization-induced stress in the SLL as revealed by micro-cantilever stress measurements.