Silicene and Germanene: A First Principle Study of Electronic Structure and Effect of Hydrogenation-Passivation

Journal of Computational and Theoretical Nanoscience (Impact Factor: 1.34). 03/2014; 11(3):1-8. DOI: 10.1166/jctn.2014.3428


Using first principle calculations we have explored the structural and electronic properties of silicene (silicon analogue of graphene) and germanene (germanium analogue of graphene). The structural optimization reveals that buckled silicene and germanene are more stable than their planar counterparts by about 0.1 and 0.35 eV respectively. In comparison to planar graphene (buckling parameter Δ = 0 Å) the germanium sheet is buckled by 0.737 Å and silicene by 0.537 Å but both have similar electronic structure with zero band gap at K point as that of graphene. Further we investigated the effects of complete hydrogenation on these materials by considering different geometrical configurations (chair, boat, table and stirrup) and found that chair-like structure has the highest binding energy per atom in comparison to other structures. Hydrogenated silicene (silicane) shows an indirect band gap of 2.23 eV while hydrogenated germanene (germanane) possess a direct band gap of 1.8 eV.

Download full-text


Available from: Anurag Srivastava, Aug 08, 2015
1,816 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: The fascinating electronic and optoelectronic properties of free-standing graphene has led to the exploration of alternative two-dimensional materials that can be easily integrated with current generation of electronic technologies. In contrast to 2D oxide and dichalcogenides, elemental 2D analogues of graphene, which include monolayer silicon (silicene), are fast emerging as promising alternatives, with predictions of high degree of integration with existing technologies. This article reviews this emerging class of 2D elemental materials – silicene, germanene, stanene, and phosphorene – with emphasis on fundamental properties and synthesis techniques. The need for further investigations to establish controlled synthesis techniques and the viability of such elemental 2D materials is highlighted. Future prospects harnessing the ability to manipulate the electronic structure of these materials for nano- and opto-electronic applications are identified.
    Small 11/2014; 11(6). DOI:10.1002/smll.201402041 · 8.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Silicon thin films were deposited on a sapphire and a highly oriented pyrolytic graphite (HOPG), which have atomically flat and chemically inert surfaces. The electronic and geometrical structures of the films were analyzed by X-ray photoelectron spectroscopy (XPS) and polarization-dependent X-ray absorption fine structure (XAFS). It was found that the silicon K-edge XAFS spectra for ultra-thin silicon films thinner than 0.2 monolayer exhibited two distinct resonance peaks which were not observed for bulk silicon. The peaks were assigned to the resonance excitations from the Si 1s into the valence unoccupied orbitals with π∗ and σ∗ characters. The average tilted angle of the π∗ orbitals was determined by the polarization dependencies of the peak intensities. It was demonstrated that direction of a part of the π∗ orbitals in silicon film is perpendicular to the surface. These results support the existence of quasi-freestanding single-layered silicon films with sp2 configuration.
    Chemical Physics 11/2014; 444. DOI:10.1016/j.chemphys.2014.09.011 · 1.65 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report the detection of ammonia gas through electronic and transport properties analysis of boron nitride sheet. The density functional theory (DFT) based ab initio approach has been used to calculate the electronic and transport properties of BN sheet in presence of ammonia gas. Analysis confirms that the band gap of the sheet increases due to presence of ammonia. Out of different positions, the bridge site is the most favorable position for adsorption of ammonia and the mechanism of interaction falls between weak electrostatic interaction and chemisorption. On relaxation, change in the bond angles of the ammonia molecule in various configurations has been reported with the distance between NH3 and the sheet. An increase in the transmission of electrons has been observed on increasing the bias voltage and I-V relationship. This confirms that, the current increases on applying the bias when ammonia is introduced while a very small current flows for pure BN sheet.
    Journal of Molecular Modeling 03/2015; 21(3). DOI:10.1007/s00894-015-2595-3 · 1.74 Impact Factor
Show more