Strain-Induced Bandgap Enhancement of InSe Ultrathin Films with Self-Formed Two-Dimensional Electron Gas
Strain-Induced Bandgap Enhancement of InSe Ultrathin Films with Self-Formed Two-Dimensional Electron Gas
复制标题
自形成二维电子气应变诱导 InSe 超薄膜带隙增强
DOI：
10.1021/acsnano.1c03724
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发表时间：
2021
期刊：
影响因子：
17.1
通讯作者：
Zhang Wenhao
中科院分区：
文献类型：
--
作者：
Zhang Zhimo;Yuan Yuan;Zhou Weiqing;Chen Chen;Yuan Shengjun;Zeng Hualing;Fu Ying-Shuang;Zhang Wenhao
原子薄的硒化铟（InSe）是一种典型的二维（2D）材料，由于其独特的物理特性和高性能的光电应用前景，近年来引起了人们的广泛兴趣。在这里，通过利用分子束外延和扫描隧道显微镜，我们报告了控制合成的InSe薄膜下降到单层的限制和表征其电子性质在原子尺度上。高度通用的生长条件被开发用于制备良好结晶的InSe薄膜，在InSe和In2Se3之间具有可逆和可控的相变。InSe薄膜的带隙尺寸随着薄膜厚度的减小而增大。在各种类型的晶格缺陷附近，带隙变得显著增大，导致横向异质结的I型带对齐。这样的带隙增强，从我们的第一性原理计算揭示，归因于局部压缩应变所施加的晶格缺陷。此外，硒化铟薄膜主机高度导电的2D电子气，表现出突出的准粒子散射签名。二维电子气是通过衬底掺杂电子自形成的，这将费米能级移动到限制量子化导带之上。我们的研究确定了InSe薄膜作为一个有吸引力的系统，在纳米电和光电子学的基础研究和潜在的应用。
Atomically thin indium selenide (InSe) is a representative two-dimensional (2D) family that have recently attracted extensive interest for their intriguing emerging physics and potential optoelectronic applications with high-performance. Here, by utilizing molecular beam epitaxy and scanning tunneling microscopy, we report a controlled synthesis of InSe thin films down to the monolayer limit and characterization of their electronic properties at atomic scale. Highly versatile growth conditions are developed to fabricate well crystalline InSe films, with a reversible and controllable phase transformation between InSe and In2Se3. The band gap size of InSe films, as enhanced by quantum confinement, increases with decreasing film thickness. Near various categories of lattice imperfections, the band gap becomes significantly enlarged, resulting in a type-I band alignments for lateral heterojunctions. Such band gap enhancement, as unveiled from our first-principles calculations, is ascribed to the local compressive strain imposed by the lattice imperfections. Moreover, InSe films host highly conductive 2D electron gas, manifesting prominent quasiparticle scattering signatures. The 2D electron gas is self-formed via substrate doping of electrons, which shift the Fermi level above the confinement-quantized conduction band. Our study identifies InSe ultrathin film as an appealing system for both fundamental research and potential applications in nanoelectrics and optoelectronics.