Next-generation storage technology: The new material is promising

 

Next-generation storage technology: The new material is promising

Phase change memory represents a novel form of nonvolatile memory harnessing the unique properties of phase change materials (PCM). These materials can seamlessly shift between an amorphous state, characterized by scattered atoms, and a crystalline state, where atoms closely align. This transition results in a reversible electrical property that can be meticulously engineered for data storage and retrieval.

Despite being a relatively nascent field, phase change memory holds the potential to revolutionize data storage due to its remarkable storage density and swift read and write capabilities. However, the intricate fabrication methods and complex switching mechanisms associated with these materials have presented significant challenges for mass production.

In recent times, two-dimensional (2D) Van Der Waals (vdW) transition metal di-chalcogenides have emerged as promising PCM candidates for use in phase change memory. Researchers from Tohoku University have shed light on the exciting prospect of employing sputtering techniques to create large-area 2D vdW tetra-chalcogenides. In employing this method, they successfully produced and identified an exceptionally promising material, niobium telluride (NbTe4), which possesses an extraordinarily low melting point of around 447 ºC (onset temperature), setting it apart from other transition metal di-chalcogenides (TMDs) .

“Sputtering is a widely employed technique that entails depositing thin material films onto a substrate, affording precise control over film thickness and composition,” explained Yi Shuang, an assistant professor at Tohoku University’s Advanced Institute for Materials Research and co-author of the study. "Our deposited NbTe4 films initially assumed an amorphous state but could be crystallized into a 2D layered crystalline phase through annealing at temperatures exceeding 272 ºC."

Unlike conventional amorphous-crystalline PCM materials like Ge2Sb2Te5 (GST), NbTe4 showcases both a low melting point and a high crystallization temperature. This distinctive combination results in reduced reset energies and enhanced thermal stability when in the amorphous phase.

Upon the successful fabrication of NbTe4, the researchers proceeded to assess its switching performance. It exhibited a significant reduction in operation energy requirements compared to traditional phase-change memory compounds. Impressively, it boasted a 10-year data retention temperature estimated to be as high as 135 ºC, surpassing the 85 ºC of GST. This suggests outstanding thermal stability, rendering NbTe4 suitable for deployment in high-temperature environments such as the automotive industry. Furthermore, NbTe4 demonstrated a rapid-switching speed of approximately 30 nanoseconds, further underscoring its potential as a next-generation phase change memory solution.

“We have opened up new possibilities for developing high-performance phase change memories,” added Shuang. "With NbTe4's low melting point, high crystallization temperature, and excellent switching performances, it is positioned as the ideal material to address some of the current challenges faced by existing PCM technologies."

[Reference: "NbTe4 Phase-Change Material: Breaking the Phase-Change Temperature Balance in 2D Van der Waals Transition-Metal Binary Chalcogenide" by Yi Shuang, Qian Chen, Mihyeon Kim, Yinli Wang, Yuta Saito, Shogo Hatayama, Paul Fons, Daisuke Ando, Momoji Kubo and Yuji Sutou, 20 June 2023, Advanced Materials.]