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Hexagonal honeycomb silicon: Silicene
Published in Klaus D. Sattler, Silicon Nanomaterials Sourcebook, 2017
Xin Tan, Sean C. Smith, Zhongfang Chen
The recent discovery of graphene has initiated tremendous interest in exploring graphene-like materials. Silicene, the silicon analogue of graphene, is a one-atom-thick silicon sheet arranged in a 2D honeycomb lattice. Although theoretical investigations have shown that freestanding silicene has the potential to be realized, freestanding silicene has not been achieved experimentally so far. Nevertheless, the epitaxial silicene has been successfully synthesized on Ag(111), Ir(111), ZrB2(0001), LaAlO3(111), and MoS2(0002) substrates.
Novel cubic silicane nanosheet as an adsorbing medium for dimethylbutane and methylhexane molecules – a first-principles study
Published in Molecular Physics, 2023
M. S. Jyothi, V. Nagarajan, R. Chandiramouli
Even before the cutting-edge research on graphene, in the year 2004, the idea of silicene as a 2D puckered honeycomb arrangement of silicon atoms was introduced [18]. In contrast to the carbon flat-state stage, the aromatic ring was projected to be more stable in a regular corrugation leading to buckled configuration with D3d group symmetry. Zhi-Gang group then confirmed this structure via ab initio simulations [19]. The buckling configuration of silicene arises from pseudo-Jahn–Teller distortion in correlation with occupied and unoccupied molecular orbitals coupling. In fact, the mixed sp3 – sp2 hybridization leads to the topological characteristic of silicene, in contrast to the sp3 hybridization in its bulk form. Though silicene is anticipated to uphold semi-metallic features associated with graphene-like Dirac fermions [20], two factors, a low symmetry with bent honeycomb structure and the significant spin–orbit coupling effect lead to silicene's characteristics diverging noticeably compared to graphene. These diverging aspects suggest that silicene could significantly benefit bandgap tuning, edge states spin polarization, and features of electronic states [21,22]. The technological associations with these attractive properties furnish the devices of silicene for photothermal therapy, gas sensors, and field effect transistors.
Engineering the electronic properties of siligraphene sheets by organic molecules: a density functional theory investigation
Published in Molecular Physics, 2021
Graphene is an intensively investigated material due to its extraordinary mechanical, electronic, thermal, as well as optical properties [1–3]. It is a two-dimensional (2D) material that consists of carbon atoms with honeycomb lattice structure. Its novel properties as well as a huge potential for nanoelectronics, sensors, spintronics, energy storage and conversion have been reported [4–9]. On the other hand, silicene is a graphene-like 2D material with low-buckled geometry, and it has also been intensively studied [10,11]. Graphene and silicene exhibit similar electronic structures. Their electronic structures reveal that both are semimetal and possess linear dispersion around the Dirac point [12,13]. The semimetallic nature of graphene and silicene limits their widespread applications for optoelectronic devices requiring tunable band gap [14,15]. Hence, it is essential to generate a finite gap of these materials. Many approaches have been proposed recently to tune their band gap energies including: substrate-induced gap, applying an external gate, resizing them into nanoribbons, chemical functionalization, doping, etc. [16–24]. Although these approaches are successful, band gap opening has been proved to be difficult to achieve experimentally [25]. Therefore, recent attention has been devoted to the design of 2D silicon-carbide based compounds with novel intrinsic semiconducting properties [26–30]. Interestingly, intensive studies of 2D nanomaterials led to the prediction or synthesis of siligraphene sheets including SiC, SiC2, SiC3, SiC5 and SiC7, with various electronic properties [15,25,26,31–39]. It was found that both stoichiometry as well as bonding structure of silicon-carbon monolayers can extensively influence their electronic properties [35]. The band gap of siligraphene can differ within the range of 0–2.5 eV, independent of silicon content [29]. Among the different siligraphene sheets, SiC3 and SiC5 are semimetal, while SiC, SiC2 and SiC7 exhibit semiconducting properties. Therefore, siligraphene sheets can be promising 2D materials for electronic and optoelectronic applications.