Browsing by Author "Lin, Shih-Yang"

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H-Si bonding-induced unusual electronic properties of silicene: a method to identify hydrogen concentration
(2015-01-01)
Lin, Shih-Yang
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Chang, Shen-Lin
;
Ngoc Thanh Thuy Tran
;
Yang, Po-Hua
;
Lin, Ming-Fa
Hydrogenated silicenes possess peculiar properties owing to the strong H-Si bonds, as revealed by an investigation using first principles calculations. Various charge distributions, bond lengths, energy bands, and densities of states strongly depend on different hydrogen configurations and concentrations. The competition between strong H-Si bonds and weak sp(3) hybridization dominate the electronic properties. Chair configurations belong to semiconductors, while the top configurations show a nearly dispersionless energy band at the Fermi level. Both the systems display H-related partially flat bands at middle energy and the recovery of low-lying pi bands during the reduction of concentration. Their densities of states exhibit prominent peaks at middle energy, and the top systems have a delta-funtion-like peak at E = 0. The intensity of these peaks is gradually weakened as the concentration decreases, providing an effective method to identify the H-concentration in scanning tunneling spectroscopy experiments.
Substrate-induced structures of bismuth adsorption on graphene: a first principles study
(2016-07-28)
Lin, Shih-Yang
;
Chang, Shen-Lin
;
Chen, Hsin-Hsien
;
Su, Shu-Hsuan
;
Huang, Jung-Chun
The geometric and electronic properties of Bi-adsorbed monolayer graphene, enriched by the strong effect of a substrate, are investigated by first-principles calculations. The six-layered substrate, corrugated buffer layer, and slightly deformed monolayer graphene are all simulated. Adatom arrangements are thoroughly studied by analyzing the ground-state energies, bismuth adsorption energies, and Bi-Bi interaction energies of different adatom heights, inter-adatom distance, adsorption sites, and hexagonal positions. A hexagonal array of Bi atoms is dominated by the interactions between the buffer layer and the monolayer graphene. An increase in temperature can overcome a similar to 50 meV energy barrier and induce triangular and rectangular nanoclusters. The most stable and metastable structures agree with the scanning tunneling microscopy measurements. The density of states exhibits a finite value at the Fermi level, a dip at similar to -0.2 eV, and a peak at similar to-0.6 eV, as observed in the experimental measurements of the tunneling conductance.