Revealing the structure and electronic characteristics of Te-rich threshold switching materials for high-density integration

Journal Article · 16 September 2024 · Journal of Materials Chemistry C

DOI: https://doi.org/10.1039/d4tc03146f · OSTI ID:2476515

Qiao, Chong  ^[1]; Gu, Rongchuan ^[2]; Hu, Shuangnian ^[1]; Wang, Guoxin ^[1]; Wang, Shengzhao ^[1]; Gong, Pei ^[1]; Wang, Songyou  ^[3]; Wang, Cai-Zhuang  ^[4]; Xu, Ming  ^[2]; Miao, Xiangshui  ^[2]

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1. Nanyang Institute of Technology (China)
2. Huazhong University of Science and Technology, Wuhan (China)
3. Fudan University, Shanghai (China)
4. Ames Laboratory, and Iowa State University, Ames, IA (United States)

Ovonic threshold switching (OTS) selectors play an important role in the integration of advanced three-dimensional memory. Selectors based on tellurium (Te)-containing materials exhibit significant promise due to their low threshold voltages and superior consistency. Here we have theoretically studied the structure and electronic properties of a typical OTS material, amorphous GeTe₆, to explore the switching mechanisms using ab initio molecular dynamics simulations. The results indicate that Ge atoms tend to bond with Te atoms, forming stable chemical bonds. The Te-centered clusters are predominantly in the form of distorted octahedrons, while the Ge-centered clusters are in the form of both octahedrons and tetrahedrons. Notably, the proportion of tetrahedrons within the 4-coordinated Ge-centered clusters reaches an impressive 66.9%. These tetrahedrons are randomly dispersed throughout the simulated cell, leading to a stable amorphous configuration. The mid-gap state observed in the mobility bandgap originates from the atomic chain composed of both over-coordinated Ge and Te atoms. It is the inherent stability of the chemical environment within amorphous GeTe₆ that enables it to maintain its amorphous phase under a repeated threshold voltage, a characteristic that distinguishes it from non-OTS materials, such as amorphous tellurium. Furthermore, our findings provide an in-depth understanding of the structure and electronic characteristics of amorphous GeTe₆, which can promote the design and application of the Te-rich threshold switching materials.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE); National Science and Technology Major Project of China; Science and Technology Department of Henan Province
• Grant/Contract Number: AC02-07CH11358
• OSTI ID: 2476515
• Report Number(s): IS-J--11,446
• Journal Information: Journal of Materials Chemistry C, Journal Name: Journal of Materials Chemistry C Journal Issue: 42 Vol. 12; ISSN 2050-7526
• Publisher: Royal Society of ChemistryCopyright Statement
• Country of Publication: United States
• Language: English