Thickness-dependent band gap of alpha-In2Se3: from electron energy loss spectroscopy to density functional theory calculations
Thickness-dependent band gap of alpha-In2Se3: from electron energy loss spectroscopy to density functional theory calculations
复制标题
α-In2Se3 的厚度相关带隙：从电子能量损失谱到密度泛函理论计算
DOI：
10.1088/1361-6528/ab8998
复制
发表时间：
2020
期刊：
影响因子：
3.5
通讯作者：
Chen Qing
中科院分区：
文献类型：
--
作者：
Lyu Fengjiao;Sun Yuanwei;Yang Qin;Tang Bin;Li Mingqiang;Li Zhiwei;Sun Mei;Gao Peng;Ye Lin-Hui;Chen Qing
α-In 2 Se 3由于其优异的电学和光学性能，近年来受到越来越多的关注。特别是，它的特殊的铁电和压电性能，大多数其他二维（2D）材料不具备已受到关注。本文首次用电子能量损失谱（EELS）测量了少层α-In 2Se 3的带隙随厚度的变化。带隙随薄膜厚度的减小而增加，薄膜厚度从48 nm厚的区域中的1.44 eV变化到样品的8 nm厚区域中的1.64 eV。此外，通过结合改进的交换相关势和适当的屏蔽的内部电场在一个先进的2D电子结构技术，我们已经能够获得密度泛函理论内的带隙的结构依赖性高达数百个原子。这也是第一次对2D铁电材料进行类似类型的计算。实验和理论都表明，α-In 2Se 3的带隙变化符合二维材料的量子限制模型.
α-In 2 Se 3 has attracted increasing attention in recent years due to its excellent electrical and optical properties. Especially, attention has been paid to its peculiar ferroelectric and piezoelectric properties which most other two-dimensional (2D) materials do not possess. This paper presents the first measurement of the thickness-dependent band gaps of few-layer α-In 2 Se 3 by electron energy loss spectroscopy (EELS). The band gap increases with decreasing film thickness which varies from 1.44 eV in a 48 nm thick area to 1.64 eV in an 8 nm thick area of the samples. Further, by combining the improved exchange-correlation potential and proper screening of the internal electric field in an advanced 2D electronic structure technique, we have been able to obtain the structural dependence of the band gap within density functional theory up to hundreds of atoms. This is also the first calculation of a similar type for 2D ferroelectric materials. Both experiment and theory suggest that the variation of the band gap of α-In 2 Se 3 fits well with the quantum confinement model for 2D materials.