Realization of Non‐Equilibrium Wurtzite Structure in Heterovalent Ternary MgSiN₂ Film Grown by Reactive Sputtering

Journal Article · Thu Feb 06 00:00:00 UTC 2025 · Advanced Electronic Materials

DOI: https://doi.org/10.1002/aelm.202400880 · OSTI ID:2997507

Kageyama, Sotaro ^[1]; Okamoto, Kazuki  ^[1]; Yasuoka, Shinnosuke ^[1]; Ide, Keisuke  ^[1]; Hanzawa, Kota  ^[1]; Hiranaga, Yoshiomi  ^[2]; Hsieh, Pochun ^[3]; Hazra, Sankalpa ^[3]; Suceava, Albert ^[3]; Saha, Akash ^[3]; Yokota, Hiroko  ^[4]; Shigematsu, Kei  ^[5]; Azuma, Masaki  ^[5]; Gopalan, Venkatraman  ^[3]; Uchida, Hiroshi  ^[6]; Hiramatsu, Hidenori  ^[1]; Funakubo, Hiroshi  ^[1]

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1. Institute of Science Tokyo, Kanagawa (Japan)
2. Tohoku University, Miyagi (Japan)
3. Pennsylvania State University, University Park, PA (United States)
4. Institute of Science Tokyo, Kanagawa (Japan); Nagoya University, Aichi (Japan)
5. Institute of Science Tokyo, Kanagawa (Japan); Kanagawa Institute of Industrial Science and Technology, Ebina (Japan)
6. Sophia Univ., Tokyo (Japan)

The piezoelectric and ferroelectric applications of heterovalent ternary materials are not well explored. Epitaxial MgSiN₂ films are grown at 600 °C on (111)Pt//(001)Al₂O₃ substrates by the reactive sputtering method using metallic Mg and Si under the N₂ atmosphere. Detailed X-ray diffraction measurements and transmission electron microscopy observations revealed that the epitaxially grown films on the substrates have a hexagonal wurtzite structure with c-axis out-of-plane orientation. The random occupation of this structure by Mg and Si differs from that of the previously reported structure in which these two cations periodically occupy the cationic sites. However, the lattice spacings closely approximate those that are previously reported, irrespective of the ordering, and they are almost comparable with those of (Al_0.8Sc_0.2)N. The wide bandgap of >5.0 eV in deposited MgSiN₂ is compatible with that of AlN and suggests durability against the application of strong external electric fields, possibly to induce polarization switching. In addition, MgSiN₂ is shown to have piezoelectric properties with an effective d₃₃ value of 2.3 pm V⁻¹ for the first time. This work demonstrates the compositional expansion of hexagonal wurtzite to heterovalent ternary nitrides for novel piezoelectric materials, whose ferroelectricity is expected.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Center for 3D Ferroelectric Microelectronics Manufacturing (3DFeM2); Pennsylvania State Univ., University Park, PA (United States); Pennsylvania State University, University Park, PA (United States)
• Sponsoring Organization: JST FOREST Program; Japan Science and Technology Agency; Japan Science and Technology Agency (JST); Japan Society for the Promotion of Science; Japan Society for the Promotion of Science (JSPS) KAKENHI; MEXT Program: Data Creation and Utilization Type Material Research and Development Project; Ministry of Education, Culture, Sports, Science and Technology; Next-generation Novel Integrated Circuits Centers (X-NICS); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0012375; SC0020145; SC0021118
• OSTI ID: 2997507
• Journal Information: Advanced Electronic Materials, Journal Name: Advanced Electronic Materials Journal Issue: 9 Vol. 11; ISSN 2199-160X
• Publisher: WileyCopyright Statement
• Country of Publication: United States
• Language: English