Laboratoire des Solides Irradiés, Ecole polytechnique, CNRS, CEA, Université Paris-Saclay, 91128 Palaiseau, France.
European Theoretical Spectroscopy Facility, 91128 Palaiseau, France.
Sci Rep. 2017 Jan 24;7:39844. doi: 10.1038/srep39844.
Dielectric screening of excitons in 2D semiconductors is known to be a highly non-local effect, which in reciprocal space translates to a strong dependence on momentum transfer q. We present an analytical model dielectric function, including the full non-linear q-dependency, which may be used as an alternative to more numerically taxing ab initio screening functions. By verifying the good agreement between excitonic optical properties calculated using our model dielectric function, and those derived from ab initio methods, we demonstrate the versatility of this approach. Our test systems include: Monolayer hBN, monolayer MoS, and the surface exciton of a 2 × 1 reconstructed Si(111) surface. Additionally, using our model, we easily take substrate screening effects into account. Hence, we include also a systematic study of the effects of substrate media on the excitonic optical properties of MoS and hBN.
二维半导体中的激子介电屏蔽是一种高度非局域的效应，在倒空间中表现为对动量转移 q 的强烈依赖。我们提出了一种解析介电函数模型，包括完整的非线性 q 依赖性，可作为更具数值挑战性的从头算屏蔽函数的替代方法。通过验证使用我们的介电函数模型计算的激子光学性质与从头算方法得出的结果之间的良好一致性，我们证明了这种方法的多功能性。我们的测试系统包括：单层 hBN、单层 MoS2 和 2×1 重构 Si(111)表面的表面激子。此外，我们使用模型可以轻松考虑衬底屏蔽效应。因此，我们还系统地研究了衬底介质对 MoS2 和 hBN 的激子光学性质的影响。
