Chalcogenide Materials Engineering for Phase‐Change Memory and Future Electronics Applications: From Sb–Te to Bi–Te

Abstract

Chalcogenide materials play essential roles in modern nonvolatile memory technology in the form of both phase‐change memory (PCM) and selector devices. Herein, Bi–Te binary alloys are explored as an alternative candidate for superlattice (SL) or interfacial PCM (iPCM). GeTe/Bi4Te3 (GT/BT) SL exhibits similar structural features to conventional GeTe/Sb2Te3 (GT/ST) SL, such as highly oriented crystal grains and intermixing. Furthermore, preliminary device measurements show that Ge–Bi–Te (GBT) SL switches in a similar manner to conventional Ge–Sb–Te (GST), suggesting that they may be a promising candidate for memory applications. In addition, Bi2Te3/Sb2Te3 (BT/ST) heterostructure films have been successfully fabricated and show clear interface stacking at the atomic level. Although the BT/ST heterostructure is ostensibly a p–n junction, rectifying behavior is not observed in current (I)–voltage (V) measurements due to the existence of a large number of carriers in both layers. Finally, density functional theory (DFT)‐based simulations suggest that an ideal BT/ST heterostructure may possess intriguing topological properties that can enable novel functional devices. The Bi–Te binary alloys offer promising potential for optimizing PCM performance as well as for the realization of novel functional electronic devices.