2025-06-23 東京科学大学
＜関連情報＞
- https://www.isct.ac.jp/ja/news/d3eu5udwrc8c
- https://www.isct.ac.jp/plugins/cms/component_download_file.php?type=2&pageId=&contentsId=1&contentsDataId=1719&prevId=&key=502abb23634ed23dccc84c74584af3a1.pdf
- https://pubs.aip.org/aip/apm/article/13/4/041120/3344895/Impact-of-film-composition-on-crystal-structure
(Al1-x-yGaxScy)N三元系ウルツ鉱薄膜の結晶構造と強誘電性に及ぼす薄膜組成の影響
Impact of film composition on crystal structure and ferroelectricity in (Al1−x−yGaxScy)N ternary wurtzite thin films
Reika Ota;Nana Sun;Kazuki Okamoto;Shinnosuke Yasuoka;Yoshihiro Ueoka;Daiki Shono;Masami Mesuda;Hiroshi Funakubo
APL Materials Published:April 22 2025
DOI:https://doi.org/10.1063/5.0261572
The wurtzite-structure ternary alloys of (Al,Ga,Sc)N films with a high Sc/(Al+Ga+Sc) ratio are successfully deposited by a reactive magnetron sputtering method. The breakthrough in ScN solid-solution limit in AlN with wurtzite structure [up to Sc/(Al + Ga + Sc) = 0.47] is achieved, and its wurtzite-phase diagram region is expanded by adding a relatively small amount of Ga [Ga/(Al+Ga+Sc) < 0.1] into the (Al,Sc)N film. The c– and a-axes lattice constants depend strongly on Ga/(Al+Ga+Sc) and Sc/(Al+Ga+Sc) ratios, respectively, and the Sc/(Al+Ga+Sc) ratio primarily determines the internal structure showing a crystal anisotropy parameter, u parameter. The dielectric constant increases with the increase of Sc/(Al+Ga+Sc) ratio. In addition, the coercive field significantly decreases from 5.8 to 1.8 MV/cm with an increasing Sc/(Al+Ga+Sc) ratio from 0.33 to 0.47, while polarization slightly reduces with the increased u parameter. This result provides a new way to expand the content of the ScN solid solution in the wurtzite film to further decrease the coercive field for the memory device applications.
