Huang Tianlun Allan, Zacharias Marios, Lewis D Kirk, Giustino Feliciano, Sharifzadeh Sahar
Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, United States.
Department of Mechanical and Materials Science Engineering, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol, Cyprus.
J Phys Chem Lett. 2021 Apr 22;12(15):3802-3808. doi: 10.1021/acs.jpclett.1c00264. Epub 2021 Apr 13.
We investigate from first principles exciton-phonon interactions in monolayer germanium selenide, a direct gap two-dimensional semiconductor. By combining the Bethe-Salpeter approach and the special displacement method, we explore the phonon-induced renormalization of the exciton wave functions, excitation energies, and oscillator strengths. We determine a renormalization of the optical gap of 0.1 eV at room temperature, which results from the coupling of the exciton with both acoustic and optical phonons, with the strongest coupling to optical phonons at ∼100 cm. We also find that the exciton-phonon interaction is similar between monolayer and bulk GeSe. Overall, we demonstrate that the combination of many-body perturbation theory and special displacements offers a new route to investigate electron-phonon couplings in excitonic spectra, the resulting band gap renormalization, and the nature of phonons that couple to the exciton.
我们从第一性原理出发，研究了单层硒化锗（一种直接带隙二维半导体）中的激子 - 声子相互作用。通过结合贝塞耳 - 萨尔皮特方法和特殊位移方法，我们探索了声子诱导的激子波函数、激发能和振子强度的重整化。我们确定在室温下光学带隙的重整化量为0.1电子伏特，这是由于激子与声学声子和光学声子的耦合所致，其中与约100厘米处的光学声子耦合最强。我们还发现单层和体相GeSe之间的激子 - 声子相互作用相似。总体而言，我们证明多体微扰理论和特殊位移的结合为研究激子光谱中的电子 - 声子耦合、由此产生的带隙重整化以及与激子耦合的声子性质提供了一条新途径。
