Papers by Keyword: Silicene

Abstract: Density-functional-theory calculations have been performed to investigate the magnetism induced in silicene and germanene by hydrogen terminations. We varied the H-terminated structures from monomers to pentamers. Silicene and germanene exhibit magnetic properties after H termination, as indicated by the appearance of magnetic moments. The greater the magnetic moment, the more H atoms are added in the same direction. Conversely, H atoms added in the opposite direction reduce the magnetic moment. We calculated the adsorption energy for each variation of H-terminated silicene and germanene. The results show that both have negative adsorption energies. H-terminated silicene has a more negative adsorption energy than H-terminated germanene. For example, pentamer silicene has an adsorption energy of -10.37 eV, while pentamer germanene has an adsorption energy of -7.39 eV. This indicates that H is more easily adsorbed on silicene. Thus, H-terminated silicene and germanene are suitable for magnetic material device applications.

Abstract: First principle calculation is performed to investigate structural and electronic properties of strained silicene (silicon analogue of graphene) when absorbing the hydrogen sulfide molecule gas. Two configuration of silicene-H₂S system, center and hollow configuration, is checked under 0% (pure), 5%, and 10% uniaxial engineering strain. We report that the silicene-H₂S system in center configuration has larger binding energy compare to the silicene-H₂S system in hollow configuration. The results show that H₂S is physisorbed on silicene. In this work, we also find the change of band gap energy (~60 meV) is appearing when H₂S interacted with silicene in center configuration, whereas the band gap energy of silicene has no change when interacted with H₂S in hollow configuration.

Abstract: This paper deals with the elastic properties of pure and nitrogen-doped silicene using density functional theory. During the compression (tension) from –2 to 2 GPa of pure and nitrogen-doped silicene, the corresponding values for the bulk modulus are obtained. It is found that the doping of the silicene structure with nitrogen has practically no effect on the value of its bulk modulus. However, the Young's modulus is increased of about 1.25 times.

Abstract: Under external electric field, a free standing silicene monolayer is investigated for the physical and electronic features using the density functional theory with norm-conserving pseudopotentials and pseudo-atomic localized basis functions. It is found that silicene tends to be flat instead of buckled as applying electric field perpendicular to the surface. We observed on some range magnitude of electric field and noticed that there is a monotonic decreasing in number of DOS near the Fermi level showing the possibility of tunable bandgap on silicene. We also found that in this higher magnitude electric field, the Dirac cone is no longer occurring at K-point while the band gap term remains direct. The asymmetry onsite potential between the Si atom at site A and B spoils the degeneracy at the K point by the presence of external or internal influence. In this work, we try to combine those influences by considering Stone Wales (SW) defect and outer z-direction of electric field as internal and external factors respectively. A non-linear correlation of the result is profoundly becoming more effective way in effort to bring remarkable band-gap in silicene monolayer.

Abstract: This study examines the nature of thermal transport properties of single layer two-dimensional honeycomb structures of silicon-germanene nanoribbon (SiGeNR), silicene nanoribbon (SiNR) and germanene nanoribbon (GeNR) which have not yet been characterized experimentally. SiGeNR, SiNR and GeNR are the allotropes of silicon-germanium, silicon and germanium, respectively, with sp² hybridization. The thermal conductivity of the materials has been investigated using Tersoff potential through LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) by performing the molecular-dynamics simulations. The temperature is varied (50 K, 77 K, 150 K, 300 K, 500 K, 700 K, 1000 K, and 1200 K) with fixed nanoribbon dimension of 50 nm × 10 nm. The length is also varied (10 nm, 20 nm, 30 nm, 40 nm, and 50 nm) while the temperature is fixed at room temperature and the width is also fixed at 10 nm. The obtained results showed that the thermal conductivity of SiGeNR at room temperature is approximately 10 times higher than GeNR and approximately 6 times higher compared to SiNR. The thermal conductivity increases as the temperature is increased from 50 K – 300 K, and as the temperature is further increased, the thermal conductivity decreases with temperature. Moreover, the thermal conductivity in SiGeNR, SiNR, and GeNR increases as the length is being increased. Predicting new features of SiGeNR, SiNR and GeNR open new possibilities for nanoelectronic device applications of group IV two-dimensional materials.

Abstract: Silicene is becoming one of the most important two-dimensional materials. In this work, EEL Spectra were calculated for α-silicene (flat), and β-silicene (low-buckled, and theoretically the most stable). Band structures were determined using the semi-empirical Tight-Binding Method considering second nearest neighbors, sp³ model, Harrison's rule, and Slater-Koster parameterization. The dielectric function was calculated within the Random Phase Approximation and a space discretization scheme. We found that, compared to bulk Si, additional resonances appear which are red-shifted. Buckling gives rise to a richer structure at low energy.

Abstract: We systematically investigated the structural stability and electronic properties of silicene-like nanotubes by potassium atoms encapsulated using density functional theory. The calculations show that all the structures of KnSi8(n+1) (n=2-12) nanowires are stable, the structural stable is proportional to the lengths of the nanowires. Electronic population analysis shows that K atoms gain electrons and Si atoms lose electrons as a whole, some electrons transferred from Si to K atoms. Because the peaks of d levels in DOS are contribution from the 3d hybridization levels of K and Si atoms, the magnetic moments derived from the orbitals hybridization. Maybe these kinds of nanowires will play an important role in spintronics and nanoelectronics.

Abstract: The structural stability and electronic properties of silicene-like nanotubes by metal atoms encapsulated were studied by first-principles. The calculations demonstrate that all the structures of nanotubes are stable, expect beryllium doped. Some nanotubes are semiconductor with small value of band gap while others are conductor, because the interaction and hybridizations decrease the band gap. Our electronic structure analysis shows that metal atoms gain electrons and Si atoms lose electrons as a whole, some electrons transferred from Si to metal atoms. We hope that our calculations will provide help to further experimental studies.