博士候選人公開演講
類石墨烯二維材料的電子和光學性質 Electronic and optical properties of graphene-like two-dimensional materials
Abstract: Graphene-like two-dimensional materials are similar to graphene in terms of their atomic structure and two-dimensional nature, but they have some differences in their electronic and optical properties. For example, graphene-like semiconductor materials may have different bandgaps or band structures compared to graphene. Additionally, graphene-like materials may exhibit stronger excitonic effects due to their finite bandgap, while graphene has weak excitonic effects due to its gapless nature. The optical properties of graphene-like materials may also differ from graphene, with the presence of additional optical excitations and plasmon modes.
In this dissertation, we reported the results of our investigation into the electronic and optical properties of graphene-like semiconductor materials, such as SiC, BN, GaN, AlN, InN, GaTe, and GaGeTe systems which were analyzed through the use of first-principles calculations. Our study reveals that these materials exhibit enrich-physical and chemical properties through active orbitals in chemical bonds, including an optimal geometric structure, electronic band structure, van Hove singularities in the density of states (DOS), the charge density distributions, band-decomposed densities, and the charge density difference. Most notably, the optical properties of graphene-like semiconductor materials display significant excitonic effects, several optical excitation peaks in the single-particle excitations, and prominent Plasmon modes in the energy loss functions, the absorption coefficients, and the reflectance spectra. Furthermore, we established a close correlation between the orbital hybridizations of the initial and final states and each optical excitation peak observed. Our theoretical framework applies to other semiconductors and emerging materials, making our research a noteworthy contribution to the field of material sciences.
In this dissertation, we reported the results of our investigation into the electronic and optical properties of graphene-like semiconductor materials, such as SiC, BN, GaN, AlN, InN, GaTe, and GaGeTe systems which were analyzed through the use of first-principles calculations. Our study reveals that these materials exhibit enrich-physical and chemical properties through active orbitals in chemical bonds, including an optimal geometric structure, electronic band structure, van Hove singularities in the density of states (DOS), the charge density distributions, band-decomposed densities, and the charge density difference. Most notably, the optical properties of graphene-like semiconductor materials display significant excitonic effects, several optical excitation peaks in the single-particle excitations, and prominent Plasmon modes in the energy loss functions, the absorption coefficients, and the reflectance spectra. Furthermore, we established a close correlation between the orbital hybridizations of the initial and final states and each optical excitation peak observed. Our theoretical framework applies to other semiconductors and emerging materials, making our research a noteworthy contribution to the field of material sciences.
