半導体材料の圧力感度を大幅向上させる熱処理法を発見（Careful heating unlocks unprecedented sensitivity to pressure in semiconductor materials）

2025-05-15 ミシガン大学

＜関連情報＞

• https://news.umich.edu/careful-heating-unlocks-unprecedented-sensitivity-to-pressure-in-semiconductor-materials/
• https://www.nature.com/articles/s41467-025-59179-2

熱アニールによりウルツ鉱型窒化物半導体の圧電性がかつてないほど向上する Unprecedented enhancement of piezoelectricity of wurtzite nitride semiconductors via thermal annealing

Shubham Mondal,Md Mehedi Hasan Tanim,Garrett Baucom,Shaurya S. Dabas,Jinghan Gao,Jiangnan Liu,Zhengwei Ye,Venkateswarlu Gaddam,Aiden Ross,Long-Qing Chen,Honggyu Kim,Roozbeh Tabrizian & Zetian Mi
Nature Communications  Published:03 May 2025
DOI:https://doi.org/10.1038/s41467-025-59179-2

Abstract

Incorporating rare-earth elements into wurtzite nitride semiconductors, such as scandium-alloyed aluminum nitride (ScAlN), significantly enhances the piezoelectric response, which is vital for a broad range of acoustic, electronic, photonic, and quantum applications. To date, however, the measured piezoelectric response of nitride semiconductors is far below what theory has predicted. Herein, we demonstrate a simple, scalable, post-growth thermal annealing process that can dramatically boost the piezoelectric response of ScAlN. We achieve a 3.5-fold increase in the piezoelectric modulus, d₃₃ for ScAlN, from 12.3 pC/N in the as-grown state to 45.5 pC/N, which is eight times larger than that of AlN commercially used in 5 G cellphones. The observed enhancement is unambiguously confirmed by three separate measurement techniques. Detailed material characterization techniques reveal that optimized annealing conditions significantly improve the macroscopic structural quality, achieving a more homogeneous and ordered domain orientation, and reduces the lattice parameter ratio (c/a) in the wurtzite crystal structure. The dramatic enhancement of d₃₃ in ScAlN thin films promises extreme frequency scaling opportunities for bulk acoustic wave resonators for beyond-5 G applications.