Feature-rich structural and electronic properties of halogen-functionalized germanene nanoribbons: A DFT study

Rich essential properties of silicon-substituted graphene nanoribbons: a comprehensive computational study

“…4(a) can account for the weak sp 2 hybridization in the pristine 1D system as distinguishable from its 2D graphene counterpart, which shows a clear separation of π and σ bands, thus regarded as indicating strong sp 2 hybridization. 41 Under various Si substitutions, the 1D band structures are greatly diversified, as shown in Fig. 3(c), (d), (e), (f), (g) and (h) for the substituted configurations (1Si) edge , (1Si) non-edge , (2Si) ortho , (2Si) meta , (2Si) para , and (7Si) 100% , respectively, in which the green and orange circles display the contribution of C atoms and Si adatoms in the energy bands.…”

“…To create the 1D GNRs in the VASP calculations, the periodic supercell direction was applied along the x direction, while the finite-size confinement of the y and z directions generated the 1D confinement, which was created by setting a vacuum space larger than 15 Å to avoid the interactions between two neighboring images. 40,41 The 1D Brillouin zone was sampled using 12 Â 1 Â 1 and 100 Â 1 Â 1 k-point meshes within the Monkhorst-Pack scheme for the structural relaxations and electronic structure calculations, respectively. The energy convergence was set at 10 À7 eV, and the maximum Hellmann-Feynman force was set to be less than 10 À2 eV Å À1 .…”

“…For atom adsorptions, guest atoms (adatoms) are adsorbed on the surface of the host GNRs to create adatomcarbon atom bonds that can greatly tune the pristine bonds as well as the fundamental properties of the host materials, in which the optimal adsorption positions of the top, hollow, and bridge sites strongly depend on the various kinds of atoms. 40,41 As a result, the fundamental properties of the host GNRs are not only altered by the adsorption of various kinds of atoms bu also by the adatom concentrations and distributions. Generally, adsorptions of different kinds of atoms can be classified into two typical types of adsorptions: p-type and n-type adsorptions, in which the p-type adsorption generates free holes in the host system owing to transferring electrons from the host atoms (donors) to the adatoms (acceptors) and vice versa.…”

“…For example, using first-principles calculations, the p-type adsorption effects of the halogen atoms on GNRs were completely revealed by D. K. Nguyen et al, in which the halogen adatoms are optimally adsorbed on the top sites of GNRs and the created halogencarbon bond lengths varied with their atomic numbers. 40,41 The shortest F-C bond lengths leading to the strongest bonding result in p-type metallic/semiconducting behaviors under different adatom concentrations and distributions, while the Cl-, Br-, I-, and At-C bond lengths are much larger than that of the former case and fully become p-type metals. Under the DFT calculations, the n-type adsorption effects of the alkali atoms on GNRs were revealed by Y. T. Lin et al, in which the optimal adsorption sites of the alkali atoms were found to be on the hollow sites of GNRs and the alkali-adsorbed systems become n-type metals with a high free electron density.…”

Adsorption of N, He and Ne on CGe nanoribbons for sensing and optoelectronic applications

“…In cases of N or B doping in zig-zag Ge nanoribbons, the system transitions from antiferromagnetic semiconducting to ferromagnetic or semimetallic semiconducting [29]. The research on C and Si doping in armchair Ge nanoribbons has illuminated potential applications in optoelectronic devices and transistors [30]. The hydrogen-functionalized pristine configuration demonstrates semiconducting properties, characterized by a buckling height of 0.73 Å.…”