2023 Fiscal Year Annual Research Report

Controlling the polarity of ScAlN via formation of cation/anion vacancy

Research Project

Project/Area Number	21K04168
Research Institution	National Institute of Advanced Industrial Science and Technology
Principal Investigator	Anggraini SriAyu 国立研究開発法人産業技術総合研究所, エレクトロニクス・製造領域, 主任研究員 (80784123)
Project Period (FY)	2021-04-01 – 2024-03-31
Keywords	ScAlN / piezoelectric / polarity inversion / sputtering / thin films
Outline of Annual Research Achievements	Previously,the polarity of ScAlN was succesfully inversed from Al-polar to N-polar by addition of Si or Ge or Sn. However, addition of carbon (C) or 2+ cation such as Mg or Zn into ScAlN could not cause polarity inversion. This fiscal year we found via XPS measurement that Si or Ge indeed exist as 4+ cation in the thin film that occupied metal site forming aluminum or cation vacancy. However C was found to form carbon-metal bond which suggested that C sits on nitrogen sites forming nitrogen or anion vacancy which transform metal bond coordination and led to polarity inversion. Thus, the presence of cation vacancy is critical for polarity inversion. On the contrary, anion vacancy caused phase transition that did not facilitate polarity inversion.
Remarks	Our work regarding polarity inversion of ScAlN has received positive attentions in the form of Best Poster Awards in JSAP Spring meeting 2023

(3 results)