SEOUL, February 08 (AJP) - Researchers at the Korea Advanced Institute of Science and Technology and Kyungpook National University have developed a technique to observe the real-time electrical switching process within nano-devices. By rapidly melting and freezing tellurium at cryogenic temperatures, the team successfully created and stabilized amorphous tellurium, a material essential for high-speed, low-power memory. This research provides a foundational understanding of how and when electrical switching occurs, offering a new blueprint for designing efficient semiconductor materials.
As artificial intelligence applications expand, computers require faster and more energy-efficient memory. The performance of these semiconductors depends on the switching principle, the mechanism by which memory materials turn electricity on and off. Tellurium has gained attention as a candidate for next-generation memory due to its ability to transition between high and low resistance states. However, tellurium is highly sensitive to heat, making it difficult to maintain its amorphous state—a disordered atomic structure similar to glass—under normal operating conditions.
The research team, led by Professor Seo Jun-gi of the Department of Chemical and Biomolecular Engineering at the Korea Advanced Institute of Science and Technology (KAIST) and Professor Lee Tae-hoon of Kyungpook National University (KNU), addressed this instability by lowering the surrounding temperature to cryogenic levels. In this environment, they applied electrical current to momentarily melt tellurium and then cooled it rapidly to lock it into an amorphous state. This method allowed the researchers to compare the electrical flow of disordered amorphous tellurium with that of regularly arranged crystalline tellurium within the same device.
Through this comparative analysis, the team identified that microscopic defects within the amorphous tellurium play a critical role in electrical conduction. The study revealed that switching occurs in two distinct stages: first, current increases sharply along these defects when a specific voltage is reached, and second, heat accumulates until the material melts. Previously, it was believed that the sudden increase in current was caused primarily by the melting process itself, but this research clarifies the specific roles of defects and thermal energy.
The researchers also successfully demonstrated a self-oscillation phenomenon, where voltage repeatedly rises and falls while maintaining the amorphous state without excessive current. This finding indicates that stable electrical switching can be achieved using only tellurium, a single-element material, without the need for complex chemical compositions.
Professor Seo Jun-gi stated that this is the first study to implement amorphous tellurium in an actual device environment and clarify the switching principle. He noted that the research sets a new standard for the study of next-generation memory and switching materials.
Heo Nam-uk, a student in the integrated master's and doctoral program at KAIST, served as the lead author. The study was published online in Nature Communications on January 13.
(Paper information)
Journal: Nature Communications
Title: On-device cryogenic quenching enables robust amorphous tellurium for threshold switching
DOI: https://bit.ly/4knBqqs
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