Design of c-Axis-oriented pnictogen chalcogenides

The ability to design and tune the local crystal structure of chalcogenide materials with the R3̅m space group in superlattices allows the performance and properties of interfacial phase-change memory materials to be engineered. Designing superlattice materials with high in-plane biaxial strain provides a further path to decrease the switching energy of memory devices. Here, we report how the hexagonal crystal lattice constants and the concomitant phonon modes of Sb₂Te₃-Bi₂Te₃, Sb₂Te₃-Bi₂Se₃, and Bi₂Te₃-Bi₂Se₃ materials can be controlled with a c-axis-oriented texture. Highly oriented iPCM superlattices composed of these pnictogen chalcogenides (Bi₂Te₃ and Bi₂Se₃) and GeTe are also demonstrated with a series of variants. This study demonstrates that pnictogen chalcogenide materials can be designed using high-throughput composition spreading. The materials that stem from this study are expected to be useful in high-speed, high endurance, and energy-efficient electronic memory devices.