1. NCCU Academic Hub
  2. 學術產出
  3. College of Science
  4. Periodical Articles
  5. Item

學術產出-Periodical Articles

Article View/Open

Publication Export

Google ScholarTM

政大圖書館

Citation Infomation

題名 Excitonic effects in the optical properties of a SiC sheet and nanotubes
作者 郭光宇
Hsueh,H. C. ; Guo, Guang-Yu ; Louie, Steven G.
貢獻者 應物所
日期 2011.08
上傳時間 24-Jan-2014 12:37:44 (UTC+8)
摘要 The quasiparticle band structure and optical properties of single-walled zigzag and armchair SiC nanotubes (SiC-NTs) as well as a single SiC sheet are investigated by ab initio many-body calculations using the GW and the GW plus Bethe-Salpeter equation approaches, respectively. Significant GW quasiparticle corrections, of more than 1.0 eV, to the Kohn-Sham band gaps from the local density approximation (LDA) calculations are found. The GW self-energy corrections transform the SiC sheet from an indirect LDA band gap to a direct band gap material. Furthermore, the quasiparticle band gaps of SiC-NTs with different chiralities behave very differently as a function of tube diameter, and this can be attributed to the difference in the curvature-induced orbital rehybridization among the different chiral nanotubes. The calculated optical absorption spectra are dominated by discrete exciton peaks due to exciton states with a high binding energy, up to 2.0 eV, in the SiC sheet and SiC-NTs. The formation of strongly bound excitons is attributed to the enhanced electron-hole interaction in these low-dimensional systems. Remarkably, the excited electron amplitude of the exciton wave function is found to peak on Si atoms near the hole position (which is on the C site) in zigzag SiC-NTs, indicating a charge transfer from an anion (hole) to its neighboring cations by photoexcitation. In contrast, this pronounced peak structure disappears in the exciton wave function in armchair SiC-NTs. Furthermore, in armchair SiC-NTs, the bound exciton wave functions are more localized and also strongly cylindrically asymmetric. The high excitation energy, 3.0 eV, of the first bright exciton, with no dark exciton below it, suggests that small-radius armchair SiC-NTs could be useful for optical devices working in the UV regime. On the other hand, zigzag SiC-NTs have many dark excitons below the first bright exciton and hence may have potential applications in tunable optoelectric devices ranging from infrared to UV frequencies by external perturbations.
關聯 Physical Review B, 84(8), 085404
資料來源 http://link.aps.org/doi/10.1103/PhysRevB.84.085404
資料類型 article
DOI http://dx.doi.org/10.1103/PhysRevB.84.085404
dc.contributor 應物所en_US
dc.creator (作者) 郭光宇zh_TW
dc.creator (作者) Hsueh,H. C. ; Guo, Guang-Yu ; Louie, Steven G.en_US
dc.date (日期) 2011.08en_US
dc.date.accessioned 24-Jan-2014 12:37:44 (UTC+8)-
dc.date.available 24-Jan-2014 12:37:44 (UTC+8)-
dc.date.issued (上傳時間) 24-Jan-2014 12:37:44 (UTC+8)-
dc.identifier.uri (URI) http://nccur.lib.nccu.edu.tw/handle/140.119/63540-
dc.description.abstract (摘要) The quasiparticle band structure and optical properties of single-walled zigzag and armchair SiC nanotubes (SiC-NTs) as well as a single SiC sheet are investigated by ab initio many-body calculations using the GW and the GW plus Bethe-Salpeter equation approaches, respectively. Significant GW quasiparticle corrections, of more than 1.0 eV, to the Kohn-Sham band gaps from the local density approximation (LDA) calculations are found. The GW self-energy corrections transform the SiC sheet from an indirect LDA band gap to a direct band gap material. Furthermore, the quasiparticle band gaps of SiC-NTs with different chiralities behave very differently as a function of tube diameter, and this can be attributed to the difference in the curvature-induced orbital rehybridization among the different chiral nanotubes. The calculated optical absorption spectra are dominated by discrete exciton peaks due to exciton states with a high binding energy, up to 2.0 eV, in the SiC sheet and SiC-NTs. The formation of strongly bound excitons is attributed to the enhanced electron-hole interaction in these low-dimensional systems. Remarkably, the excited electron amplitude of the exciton wave function is found to peak on Si atoms near the hole position (which is on the C site) in zigzag SiC-NTs, indicating a charge transfer from an anion (hole) to its neighboring cations by photoexcitation. In contrast, this pronounced peak structure disappears in the exciton wave function in armchair SiC-NTs. Furthermore, in armchair SiC-NTs, the bound exciton wave functions are more localized and also strongly cylindrically asymmetric. The high excitation energy, 3.0 eV, of the first bright exciton, with no dark exciton below it, suggests that small-radius armchair SiC-NTs could be useful for optical devices working in the UV regime. On the other hand, zigzag SiC-NTs have many dark excitons below the first bright exciton and hence may have potential applications in tunable optoelectric devices ranging from infrared to UV frequencies by external perturbations.en_US
dc.format.extent 560930 bytes-
dc.format.mimetype application/pdf-
dc.language.iso en_US-
dc.relation (關聯) Physical Review B, 84(8), 085404en_US
dc.source.uri (資料來源) http://link.aps.org/doi/10.1103/PhysRevB.84.085404en_US
dc.title (題名) Excitonic effects in the optical properties of a SiC sheet and nanotubesen_US
dc.type (資料類型) articleen
dc.identifier.doi (DOI) 10.1103/PhysRevB.84.085404en_US
dc.doi.uri (DOI) http://dx.doi.org/10.1103/PhysRevB.84.085404en_US