title: Investigating the electronic properties of silicon nanosheets by first-principles calculations.
abstract: Using first-principles total energy calculations within the density functional theory (DFT), we investigated the electronic and structural properties of graphene-like silicon sheets. Our studies were performed using the LSDA (PWC) and GGS (PBE) approaches. Two configurations were explored: one corresponding to a defect-free layer (h-Si), and the other to a layer with defects (d-Si), both of which were in the armchair geometry. These sheets contained clusters of the C(n)H(m) type. We also investigated the effects of doping with group IV-A elements. Structural stability was studied by only considering positive vibration frequencies. Results showed that both h-Si and d-Si present a corrugated structure with concavity. h-Si sheets were found to be ionic (D.M. = 0.33 Debye) with an energy gap (HOMO-LUMO) of 0.77 eV in the LSDA theory and 0.76 eV in the GGS approach, while d-Si sheets were observed to be covalent (D.M. = 2.78 D), and exhibited semimetallic electronic behavior (HOMO-LUMO gap = 0.32 eV within the LSDA theory and 0.33 eV within the GGS approach). d-Si sheets doped with one carbon or one germanium preserved the polarity of the undoped d-Si sheets, as well as their semimetallic electronic behavior. However, when the sheets were doped with two C or two Ge atoms, or with one of each atom (to give Si(52)CGeH(18)), they retained the semimetallic behavior, but they changed from having ionic character to covalent character.
authors.affiliation: Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Puebla, México. ernesto.chigo@correo.buap.mx
authors.forename: Ernesto
authors.initials: E
authors.lastname: Chigo Anota
authors.forename: Alejandro
authors.initials: A
authors.lastname: Bautista Hernández
authors.forename: Miguel
authors.initials: M
authors.lastname: Castro
authors.forename: Gregorio
authors.initials: G
authors.lastname: Hernández Cocoletzi
mesh_terms: D004581:Electronics; D004583:Electrons; D006108:Graphite / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D011789:Quantum Theory; D012825:Silicon / Q000737:chemistry*; D013816:Thermodynamics; D014732:Vibration
chemical_list: D006108:Graphite; D012825:Silicon