Electronic and Optical Properties of Silicon Carbide Nanostructures

• Published in: Silicon-Based Nanomaterials Vol. 187; pp. 139 - 159
• Main Authors: Guo, Guang-Yu, Hsueh, Hung-Chung, Louie, Steven
• Format: Reference Book Chapter
• Language: English
• Published: United States Springer 01.01.2013; Springer New York
• Series: Springer Series in Materials Science
• Subjects: Bright Exciton; Dark Exciton; Density functional theory; Excitonic Effect; Large Binding Energy; Laser technology & holography; Local Density Approximation; Monomolecular films; Nanotechnology; Precision instruments manufacture; Silicon; Silicon carbides
• ISBN: 9781461481683; 1461481686
• ISSN: 0933-033X; 2196-2812
• DOI: 10.1007/978-1-4614-8169-0_7

The electronic and optical properties of quasi-one-dimensional single-walled zigzag/armchair silicon-carbide nantotubes (SiC-NTs) as well as a two-dimensional SiC monolayer are investigated by ab initio methods. In order to elucidate many-electron effects on SiC nanosystems, we apply the ab initio many-body Green’s function approach to calculate the quasiparticle and optical properties of SiC nanostructures. The significant band gap correction, more than 1 eV, to the Kohn-Sham gap of density functional theory within the local density approximation of semiconducting SiC-NTs and a SiC monolayer is mainly due to the many-electron interaction effect, which is included in the GW approximation for the electron self energy. Furthermore, taking into account electron-hole interaction, the optical spectra of SiC-NTs are calculated by solving the Bethe-Salpeter equation (BSE) for the electron-hole amplitudes. Our GW+BSE calculations reveal the presence of excitons with a large binding energy as well as strong anisotropy in the optical properties in the low-dimensional SiC systems. The characteristics of the strongly bound electron-hole pairs or excitons in SiC nanostructures are also discussed in terms of the corresponding excitonic wavefunctions.