探索Bi2SeO5的高介电性能:从块体到双层和单层
Exploring the high dielectric performance of Bi2SeO5:from bulk to bilayer and monolayer
董欣月 1何育彧 1管乐 1祝元昊 2吴金雄 1付会霞 3颜丙海4
作者信息
- 1. Tianjin Key Lab for Rare Earth Materials and Applications,Center for Rare Earth and Inorganic Functional Materials,Smart Sensor Interdisciplinary Science Center,School of Materials Science and Engineering,Nankai University,Tianjin 300350,China
- 2. Center of Quantum Materials and Devices,College of Physics,Chongqing University,Chongqing 401331,China
- 3. Center of Quantum Materials and Devices,College of Physics,Chongqing University,Chongqing 401331,China;Chongqing Key Laboratory for Strongly Coupled Physics,Chongqing University,Chongqing 401331,China
- 4. Department of Condensed Matter Physics,Weizmann Institute of Science,Rehovot 7610001,Israel
- 折叠
摘要
Bi2SeO5是一种具有优异电绝缘性能的范德华(vdW)层状介电材料,引起了极大关注.然而,目前关于Bi2SeO5的研究主要停留在实验层面,仍然缺乏对其原子级薄膜的介电性能的相关理论认识.本文通过第一性原理计算确定了Bi2SeO5的介电性能,发现其块体、双层和单层均具有超高平均介电常数(εr＞20).研究表明,单层Bi2SeO5与双层Bi2O2Se之间的导带和价带能量偏移量均大于1 eV,表明单层Bi2SeO5依然可作为原子薄Bi2O2Se的良好介电层.此外,不同于h-BN或其他2D vdW绝缘体,Bi2SeO5的εr由其离子部分主导,且随着厚度的减小几乎保持不变.计算发现,单层Bi2SeO5的等效氧化层厚度可薄至0.3 nm,且单层Bi2SeO5在拉伸或压缩应变达到6％时均能保持高介电常数,这极大地促进了它与各种二维半导体的集成.本工作证明单层Bi2SeO5可以作为高性能二维电子器件良好的封装和介电层.
Abstract
Bi2SeO5 has garnered considerable attention as a van der Waals(vdW)layered dielectric material featuring excellent electrical insulation properties.However,the related theoretical understanding of the dielectric properties of atomically thin films is still lacking.Here,we conducted the first-principles calculations to determine the dielectric per-formance of Bi2SeO5,showing a high average dielectric con-stant(ε)of＞20 ranging from bulk to bilayer and monolayer.Besides,the conduction and valance band offsets between the monolayer Bi2SeO5 and bilayer Bi2O2Se were calculated to be greater than 1 eV,suggesting that monolayer Bi2SeO5 works well as the dielectric for atomically thin Bi2O2Se.Unlike h-BN or other two-dimensional(2D)vdW insulators,e of Bi2SeO5 is dominated by its ionic component and remains nearly con-stant as the thickness decreases,demonstrating an ultralow equivalent oxide thickness(EOT)of 0.3 nm for its monolayer form.Moreover,the high e of monolayer Bi2SeO5 survives under tensile or compressive strains up to 6％,which greatly facilitates its integration with various 2D semiconductors.Our work suggests that Bi2SeO5 ultrathin films can serve as ex-cellent atomically flat encapsulation and dielectric layers for high-performance 2D electronic devices.
关键词
Bi2SeO5/high-κ/equivalent oxide thickness/dielectric constant/van der Waals/first-principles calculationsKey words
Bi2SeO5/high-κ/equivalent oxide thickness/dielectric constant/van der Waals/first-principles calculations引用本文复制引用
基金项目
国家自然科学基金(92064005)
国家自然科学基金(12104072)
国家自然科学基金(12147102)
Chongqing Research Program of Basic Research and Frontier Technology,China(cstc2021jcyjmsxmX0640)
中央高校基本科研业务费专项(2023CDJXY-048)
出版年
2024
NETL
NSTL
万方数据