Structural and Ferroelectric Transition in Few-Layer HfO_(2) Films by First Principles Calculations  

作　　者：Ruiling Gao Chao Liu Bowen Shi Yongchang Li Bing Luo Rui Chen Wenbin Ouyang Heng Gao Shunbo Hu Yin Wang Dongdong Li Wei Ren 高瑞灵;刘超;施博文;李永昌;罗兵;陈睿;欧阳文彬;高恒;胡顺波;王音;李东栋;任伟(Materials Genome Institute,State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of High Temperature Superconductors,International Center of Quantum and Molecular Structures,Physics Department,Institute for the Conservation of Cultural Heritage,Shanghai University,Shanghai 200444,China;Hefei National Research Center for Physical Sciences at the Microscale,University of Science and Technology of China,Hefei 230026,China;Shanghai World Foreign Language Academy,Shanghai 200233,China;Key Laboratory of Silicate Cultural Relics Conservation(Ministry of Education),Shanghai University,Shanghai 200444,China;Hongzhiwei Technology(Shanghai)Co.,Ltd.,Shanghai 201206,China;Zhangjiang Laboratory,Shanghai 201210,China)

机构地区：[1]Materials Genome Institute,State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of High Temperature Superconductors,International Center of Quantum and Molecular Structures,Physics Department,Institute for the Conservation of Cultural Heritage,Shanghai University,Shanghai 200444,China [2]Hefei National Research Center for Physical Sciences at the Microscale,University of Science and Technology of China,Hefei 230026,China [3]Shanghai World Foreign Language Academy,Shanghai 200233,China [4]Key Laboratory of Silicate Cultural Relics Conservation(Ministry of Education),Shanghai University,Shanghai 200444,China [5]Hongzhiwei Technology(Shanghai)Co.,Ltd.,Shanghai 201206,China [6]Zhangjiang Laboratory,Shanghai 201210,China

出　　处：《Chinese Physics Letters》2024年第8期94-106,共13页中国物理快报（英文版）

基　　金：supported by the National Key R&D Program of China(Grant No.2023YFB4402600);the National Natural Science Foundation of China(Grant Nos.12074241,11929401,52130204,12311530675,and 52271007);Key Research Project of Zhejiang Lab(Grant No.2021PE0AC02);Science and Technology Commission of Shanghai Municipality(Grant Nos.22XD1400900,20501130600,21JC1402700,and 21JC1402600);supports from the open projects of Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials(Anhui University of Technology),Ministry of Education(Grant No.GFST2022KF08);State Key Laboratory of Surface Physics(Fudan University)(Grant No.KF202210);State Key Laboratory of Infrared Physics,Shanghai Institute of Technical Physics,Chinese Academy of Sciences(Grant No.SITP-NLIST-YB-2022-08);the support of China Scholarship Council,and thanks Mr.Xiaowen Shi(from HZWTECH)for helpful discussions.

摘　　要：The discovery of ferroelectricity in HfO_(2)-based materials with high dielectric constant has inspired tremendous research interest for next-generation electronic devices.Importantly,films structure and strain are key factors in exploration of ferroelectricity in fluorite-type oxide HfO_(2) films.Here we investigate the structures and straininduced ferroelectric transition in different phases of few-layer HfO_(2) films(layer number𝑁=1–5).It is found that HfO_(2) films for all phases are more stable with increasing films thickness.Among them,the Pmn2_(1)(110)-oriented film is most stable,and the films of𝑁=4,5 occur with a𝑃21 ferroelectric transition under tensile strain,resulting in polarization about 11.8μC/cm^(2) along in-plane𝑎-axis.The ferroelectric transition is caused by the strain,which induces the displacement of Hf and O atoms on the surface to non-centrosymmetric positions away from the original paraelectric positions,accompanied by the change of surface Hf–O bond lengths.More importantly,three new stable HfO_(2)2D structures are discovered,together with analyses of computed electronic structures,mechanical,and dielectric properties.This work provides guidance for theoretical and experimental study of the new structures and strain-tuned ferroelectricity in freestanding HfO_(2) films.

关 键 词：properties FERROELECTRIC POSITIONS 

分 类 号：O469[理学—凝聚态物理]