August 5, 2024
Tohoku University
Keio University
Highlights of the Announcement
Beyond complex chalcogenide-based phase-change materials (PCMs) based on the rare and toxic metal tellurium (Te), we discovered that the common and structurally simple chromium nitride (CrN) exhibits a large change in electrical resistance through a fast phase change.
We achieved a phase change in chromium nitride with an electrical resistance ratio of over 10^5 and a high-speed operation of 30 nanoseconds (ns). This fast and large change in electrical resistance is a useful property for information storage materials.
We confirmed that CrN-type phase-change memory devices can operate with lower power than conventional PCMs because they function through the slight movement of nitrogen atoms and changes in the crystal structure.
In recent years, with the advancement of the Internet of Things (IoT), artificial intelligence (AI), and big data analytics, the demand for high-speed, high-capacity non-volatile memory (NVM) has been rapidly increasing. To meet these needs, phase-change random-access memory (PCRAM), which has a simple device structure, is gaining attention. The information storage layer of existing PCRAM uses phase-change materials (PCM) based on the chalcogen element tellurium (Te). However, a challenge is the high operating power required, as significant thermal energy is needed for the amorphization of the PCM.
A research group led by Assistant Professor Yi Shuang of the Advanced Institute for Materials Research (WPI-AIMR) at Tohoku University, Professor Yuji Sutou of the university's Graduate School of Engineering (also of WPI-AIMR), and Professor Paul Fons of the Faculty of Science and Technology at Keio University has discovered that chromium nitride (CrN) undergoes a phase change in nanoseconds induced by high-speed Joule heating, resulting in a large change in electrical resistance (over five orders of magnitude). This CrN-based PCM operates at high speeds similar to commercial germanium-antimony-tellurium (Ge-Sb-Te (GST))-based PCMs and can reduce operating energy by an order of magnitude. CrN, also known as a hard coating for cutting tools, is chemically stable, more environmentally friendly than chalcogenide-based PCMs, and holds promise as a new green memory material.
This research was published in the American Chemical Society journal ACS Nano on August 1, 2024 (local time).
For the full press release, please see below.