Phase-change materials based on amorphous equichalcogenides

Abstract

Phase-change materials, demonstrating a rapid switching between two distinct states with a sharp contrast in electrical, optical or magnetic properties, are vital for modern photonic and electronic devices. To date, this effect is observed in chalcogenide compounds based on Se, Te or both, and most recently in stoichiometric Sb2S3 composition. Yet, to achieve best integrability into modern photonics and electronics, the mixed S/Se/Te phase change medium is needed, which would allow a wide tuning range for such important physical properties as vitreous phase stability, radiation and photo-sensitivity, optical gap, electrical and thermal conductivity, non-linear optical effects, as well as the possibility of structural modification at nanoscale. In this work, a thermally-induced high-to-low resistivity switching below 200 °C is demonstrated in Sb-rich equichalcogenides (containing S, Se and Te in equal proportions). The nanoscale mechanism is associated with interchange between tetrahedral and octahedral coordination of Ge and Sb atoms, substitution of Te in the nearest Ge environment by S or Se, and Sb–Ge/Sb bonds formation upon further annealing. The material can be integrated into chalcogenide-based multifunctional platforms, neuromorphic computational systems, photonic devices and sensors.

Nonvolatile Memristive Materials and Physical Modeling for In‐Memory and In‐Sensor Computing

“…Recent studies reveal that the majority of Ge atoms are tetrahedrally coordinated, which leads to the umbrella flip concept for rapid crystallization. [51,116] However, AIMD simulations demonstrated that the majority of Ge atoms were in defective octahedral coordination. [105,117] The tetrahedral Ge units are locally stabilized by quenched-in homopolar Ge─Ge bonds and are projected to vanish during structural relaxation.…”

A Light‐Programmed Rewritable Lattice‐Mediated Multistate Memory for High‐Density Data Storage

“…PCM utilizes the property of these materials to switch between a crystalline state and an amorphous state through the application of heat, and stores information by controlling the state of the material. [15][16][17] Ferroelectric memory, on the other hand, takes advantage of the critical feature of ferroelectric materials, which can maintain multiple stable polarization states that can be switched by applying an external electric field. [18,19] These NVM technologies offer ultra-fast writing/erasing speed and ultra-low power consumption, making them attractive alternatives for energy-efficient, high-speed memory applications.…”

Effect of Bi Additive on the Physical Properties of Ge2Se3-Based Equichalcogenide Glasses and Thin Films

“…Using this approach, most of the binary and ternary ChG systems have been studied, and compositional dependences of major physical/chemical properties have been documented throughout their entire glass-forming regions. − Mixing more than three constituents in multicomponent ChG composition opens a wider range of possibilities for improving and tailoring the medium properties, but simultaneously complicates the understanding of the ChG structure. Recent advances in the multicomponent ChG have led to the discovery of so-called ‘equichalcogenide’ family (ChG containing three chalcogens S, Se, and Te, simultaneously) with unique properties that can be explored in the all-chalcogenide photonic/electronic integrated platforms. , The multifunctional platforms that are based on a single-family material are very appealing because they can combine various effects in one medium using the same technological process. In particular, it is shown that amorphous materials of Ge–Sb–S–Se–Te equichalcogenide family can combine a high thermal stability, IR transparency, high sensitivity to the external influences (radiation, light, temperature) and phase-change memory effect .…”