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Discovery of electrical switching in chalcogenide glasses by S.R. Ovshinsky paves a new path for developing high‐speed nonvolatile electronic memory and high‐performance computing solutions. This article presents a review on the systematic understanding of threshold switching (TS) properties in various chalcogenide materials, Ovonic threshold switching (OTS) and Ovonic memory switching (OMS), the nature of TS, voltage‐dependent transient characteristics, and the role of TS in governing the programming speed based on research efforts over the last six decades. Furthermore, realization of TS in picosecond timescale, the commonalities between OTS and OMS, and the possible underlying mechanism has been explored. Furthermore, a scheme of material classification based on TS dynamics for ultrafast yet energy‐efficient programming has been proposed for phase‐change memory with SRAM‐like programming speed for future electronics. [ABSTRACT FROM AUTHOR]

To passivate Si−SiO2 dangling bonds, metal–oxide–semiconductor field‐effect transistor devices are usually treated with hydrogen. Herein, the effects of such a treatment on the crystallization behavior on N‐doped, Ge‐rich Ge2Sb2Te5 phase‐change materials for memory applications are investigated using synchrotron X‐ray diffraction (XRD) in situ during heat treatment. Uniform thin films, and laterally confined, metallized ones (simulating devices of different complexity) of initially amorphous N‐doped GGST are investigated. The specimens are heated up to 450–500 °C at a rate of 2 °C/min. Some of the specimens are treated with H/D; the equivalent untreated specimen is investigated for each of them. Crystallization onsets are estimated by quantification of the crystallized quantity during material transformation from the XRD patterns. In thin films, the hydrogen treatment results in lowered crystallization temperatures of the emerging cubic, metastable Ge2Sb2Te5 phase. Its trigonal, thermodynamically stable polymorph always forms, but its crystallization temperature is unchanged. Patterned and metallized samples show less differences, are strongly textured, and no trigonal phase is observed. It is shown that certain questions might only be answered at large‐scale facilities where high energy photons are available at high flux, allowing data acquisition during the annealing process with a temperature resolution sufficient for a fine description of the sample transformation. [ABSTRACT FROM AUTHOR]

Phase‐change materials (PCMs) used in data storage devices have unique structural features and transition properties by thermal heating. Pressure, as another important thermodynamic tool, can also induce a series of interesting phase transitions in PCMs, accompanied by the altering of bonding nature and physical properties. Here, the structure transition as well as property change of prototypical phase‐change material Ge–Sb–Te (GST) under hydrostatic pressure has been reviewed. The high‐pressure behavior of some other relevant chalcogenides such as GeTe, Sb2Te3, and GeSe, is also discussed. The revealing of structure and property changes due to high pressure sheds light on the underlying physics of many fascinating properties of PCMs, and therefore it will have profound implications on various applications of phase change materials in memory and other fields. The recent progress in studying the high‐pressure behavior of phase‐change materials (PCMs) has been reviewed in this article. The unique structure and property transitions of these materials, which are widely used in data storage and other electronic devices, reveal rich physics under high pressure, allowing researchers to fully understand the transition mechanism of PCMs. [ABSTRACT FROM AUTHOR]