Materials Science and Applications of Phase Change Memory Materials

Dear Colleagues,

Rapid development and the increasing number of Internet of Things devices require real time processing and storage of a huge amount of digital data. Phase change memory (PCM) is one of the most promising non-volatile technologies suited to the current demands of computing systems. The PCM utilizes chalcogenide-based phase change alloys, typically lying along the GeTe-Sb₂Te₃ quasibinary tie line. The working principle of conventional PCM relies on fast, reversible phase transitions between crystalline and amorphous states of Ge-Sb-Te-based alloys. For data storage, PCM uses a large contrast of either electrical resistance or optical reflectivity between the amorphous and crystalline state. This concept was originally proposed by S.R. Ovshinsky in the late 1960s. PCM technology was first commercialized in optical storage media such as DVD-RW and Blu-Ray discs. PCM offers multilevel data storage and can be applied in both neuro-inspired and all-photonic in-memory computing, eliminating the von Neumann bottleneck associated with the shuttling of data between CPU and memory units. The scalability of PCM results in a high integration capacity and the production of Optane memory, which was jointly development by Intel and Micron. In this technology, nanoscale Ge-Sb-Te alloys are used as memory units for data storage. In addition to chalcogenide-based phase change alloys, an oxide material such as vanadium oxide (VO₂) demonstrates huge potential as a phase change material. The VO₂ exhibits rapid, reversible, structural phase changes between the monoclinic M1 and rutile tetragonal crystalline phases, which are accompanied by insulator to metal (IMT) phase transition.

Due to the enormous potential for memory applications, significant effort has been devoted to understanding the properties of different phase change materials with the particular aim to design universal memory. However, to achieve these technological advances, a detailed understanding of fundamental properties and the functionality of those materials is still required. This Special Issue focuses on the material science aspects and applications of chalcogenide- and oxide-based phase change materials relevant for non-volatile memory applications. Experimental and theoretical works focusing on material growth, properties, and potential applications of phase change materials are welcome in the issue.

The research topics will include:

• Growth and characterization of phase change thin films and superlattices;
• Preparation and properties of nanoscale and composite phase change materials;
• Optical phase change materials for photonic computing;
• Electrical and optical switching of phase change compounds;
• Understanding material and device properties by experiment and theory;
• Novel phase change alloys for automotive applications and neuromorphic computing.

Dr. Andriy Lotnyk
Guest Editor

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• phase change materials
• chalcogenide alloys
• oxide materials
• memory materials
• phase transformations
• thin film growth
• optical switching
• resistive switching
• microstructure