Maity Nikhilesh, Srivastava Pooja, Mishra Himani, Shinde Ravindra, Singh Abhishek Kumar
Materials Research Centre, Indian Institute of Science, Bangalore 560012, India.
Amity School of Applied Sciences, Amity University Uttar Pradesh, Lucknow, Uttar Pradesh 226010, India.
J Phys Chem Lett. 2021 Feb 25;12(7):1765-1771. doi: 10.1021/acs.jpclett.0c03469. Epub 2021 Feb 11.
Stacking two or more two-dimensional materials to form a heterostructure is becoming the most effective way to generate new functionalities for specific applications. Herein, using GW and Bethe-Salpeter equation simulations, we demonstrate the generation of linearly polarized, anisotropic intra- and interlayer excitonic bound states in the transition metal monochalcogenide (TMC) GeSe/SnS van der Waals heterostructure. The puckered structure of TMC results in the directional anisotropy in band structure and in the excitonic bound state. Upon the application of compressive/tensile biaxial strain dramatic variation (∓3%) in excitonic energies, the indirect-to-direct semiconductor transition and the red/blue shift of the optical absorption spectrum are observed. The variations in excitonic energies and optical band gap have been attributed to the change in effective dielectric constant and band dispersion upon the application of biaxial strain. The generation and control over the interlayer excitonic energies can find applications in optoelectronics and optical quantum computers and as a gain medium in lasers.
堆叠两种或更多种二维材料以形成异质结构正成为为特定应用生成新功能的最有效方法。在此，通过GW和贝叶斯-萨尔皮特方程模拟，我们展示了在过渡金属硫族化物（TMC）GeSe/SnS范德华异质结构中线性极化、各向异性的层内和层间激子束缚态的产生。TMC的褶皱结构导致能带结构和激子束缚态出现方向各向异性。施加压缩/拉伸双轴应变时，激子能量会发生显著变化（∓3%），同时观察到间接半导体到直接半导体的转变以及光吸收光谱的红移/蓝移。激子能量和光学带隙的变化归因于施加双轴应变时有效介电常数和能带色散的变化。层间激子能量的产生和控制可应用于光电子学和光量子计算机，并作为激光中的增益介质。
