【摘要】 本文利用第一性原理，研究了单层和三层MoS₂的电子结构和光学性能，包括电子能带结构，以及能量在0-15eV区域内的介电常数、吸收谱、折射率和电子能量损失谱。在态密度上，两者的导带在高能量部分有区别。平衡状态下，单层MoS₂在平行于层方向（Ex）和垂直于层方向（Ez）的介电常数分别为6.69和3.89,三层MoS₂介电常数分别为15.01和8.39。单层MoS₂的介电常数曲线比三层的介电常数曲线具有精细结构。在0～6eV能量范围内，介电常数具有高度的各向异性。当能量大于7eV时，介电常数变为各向同性。在Ex方向上，单层和三层MoS₂在可见光区位置处都有一吸收峰；单层MoS₂对近紫外更敏感，而三层MoS₂对远紫外更敏感。随着层数的增加，折射率增大。单层和三层MoS₂消光系数在近紫外区的峰值都大于在远紫外区的峰值。通过电子能量损失谱可以看出随着层数的增加，峰值的位置越来越往高频区域移动。更多还原

【Abstract】 In this paper, the electronic structure and optical properties of monolayer and three-layer MoS₂ are studied using first-principles calculations. The optical characters such as: dielectric function, optical reflectivity, and electron energy-loss spectrum of MoS₂ are observed in the energy region from 0 to 15 eV. To the density of states, the conduction band of three-layers of MoS₂ has only the low-energy part. At the equilibrium state, the dielectric constants of monolayer MoS₂ in the parallel Ex and Ez directions are 6.69 and 3.89, respectively, and that in the three-layer MoS₂ is 15.01 and 8.39, respectively. The dielectric function curve of monolayer MoS₂ has a fine structure than that of three-layer MoS₂.The dielectric functions have highly anisotropic in the energy range from 0 to 6 eV but they become isotropic when the energy is larger than 7 eV. In the Ex direction, monolayer and three-layer MoS₂ have an absorption peak in the visible region. Monolayer MoS₂ is more sensitive to near ultraviolet, while three-layer MoS₂ is more sensitive to far ultraviolet. As the number of layers increases, the refractive index increases. Both Monolayer and three-layer MoS₂ extinction coefficient curves have higher peaks in the near ultraviolet region than in the far ultraviolet area. It can be seen from the electron energy loss spectrum that with the increase in the number of layers, the peak position moves more and more to the high frequency area.更多还原