[20p-S221-1~17] 13.3 Insulator technology

▼ [20p-S221-14] New finding of ferroelectricity of N doped HfO₂ films

〇(D)Lun Xu¹, Tomonori Nishimular¹, Shigehisa Shibayama¹, Takeaki Yajima¹, Shinji Migita², Akira Toriumi¹ (1.Univ. Tokyo, 2.AIST)

Keywords:HfO2,ferroelectricity,N doping

The ferroelectricity of HfO₂ can be enhanced by moderate cation doping, such as Si, Al, Y, Sr, and Zr. For Y doped HfO₂, earlier reports indicate that tetragonal and cubic phases of HfO₂ are stabilized due to trivalent Y doping induced oxygen vacancies (Vo). However, it is not well understood about the origin of HfO₂ ferroelectricity, and if it is related to the Vo or local chemical bonds. Here, N doped HfO₂ (N:HfO₂) were investigated, and we observed that ferroelectricity of HfO₂ is much more sensitive to N doping than Y doping. 0.7 mol% Y doping can maximize ferroelectricity while 0.1 mol% N doping is enough. Therefore, except Vo, we think Hf-N bonds need to be seriously considered for the ferroelectricity.