Dzujah Diyan Unmu, Pradipto Abdul-Muizz, Hidayat Rahmat, Nakamura Kohji
Physics of Magnetism and Photonics Research Division, Physics Study Program, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology Jl. Ganesha 10 Bandung Indonesia
Department of Physics Engineering, Faculty of Engineering, Graduate School of Engineering, Mie University Tsu Mie 514-8507 Japan.
RSC Adv. 2023 Jan 5;13(2):1446-1454. doi: 10.1039/d2ra06446d. eCollection 2023 Jan 3.
Graphene doped with different transition metal (TM) atoms, namely, Co, Ni, Cu, Zn, and Au, have been investigated through first-principles calculations. The TM atom forms a substitutional defect, replacing one carbon atom in the graphene basal plane, which considerably can be obtained through wet or dry chemical processes as reported elsewhere. The calculation results showed that TM atom substitution leads to the opening of a band gap and the emergence of mid-gap states with the Fermi energy in the middle of it. The effects on optical properties were seen from the calculated optical absorption and Electron Energy Loss Spectroscopy (EELS) spectra. Two EELS bands are seen in the far UV region corresponding to the π and (π + σ) plasmons but the influence of the substituted TM effects on the plasmon frequency is small. On the other hand, as the Fermi energy level appears in the middle of the mid-gap state band while the real part of its dielectric permittivity at low photon energy is negative, these TM-doped graphene have a metal-like characteristic. Hence, plasmon wave excitation can be expected at the THz region which is dependent on the dopant TM atom. The plasmon excitation in these TM-doped graphene is thus principally similar to the plasmonic excitation in pure graphene by electric or magnetic fields, where the Fermi energy level is shifted from the graphene Dirac point leading to the possibility of an intraband transition.
通过第一性原理计算研究了掺杂不同过渡金属（TM）原子（即Co、Ni、Cu、Zn和Au）的石墨烯。TM原子形成一个替代缺陷，取代石墨烯基面中的一个碳原子，如其他地方所报道的，这可以通过湿化学或干化学过程大量获得。计算结果表明，TM原子替代导致带隙打开，并在带隙中间出现费米能的中间能隙态。从计算的光吸收和电子能量损失谱（EELS）光谱中可以看出对光学性质的影响。在远紫外区域可以看到两个EELS带，对应于π和（π + σ）等离激元，但取代的TM效应对等离激元频率的影响很小。另一方面，由于费米能级出现在中间能隙态带的中间，而其在低光子能量下的介电常数实部为负，这些TM掺杂的石墨烯具有类似金属的特性。因此，可以预期在太赫兹区域会有等离激元波激发，这取决于掺杂的TM原子。因此，这些TM掺杂石墨烯中的等离激元激发原则上类似于纯石墨烯中通过电场或磁场的等离激元激发，其中费米能级从石墨烯狄拉克点移动，导致带内跃迁的可能性。
