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- Chafai, A., et al.
(författare)
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First-principles insights into the optical and electronic characteristics of barium intercalated AB-stacked bilayer graphene
- 2023
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Ingår i: The European Physical Journal Plus. - : Springer Nature. - 2190-5444. ; 138:8
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Tidskriftsartikel (refereegranskat)abstract
- The present study describes the electronic and optical characteristics of barium atoms (an alkaline earth metal) intercalated within AB-stacked bilayer graphene (AB-2LG). Using state-of-the-art first-principles computations and taking into account the dispersion forces between the diverse nanosheets, we determined that the intercalation of barium atoms (Ba) into AB-2LG increases the interlayer distance from 3.357 to 5.584 degrees A, and no C-Ba bond formation has been observed. In addition, our findings reveal that the presence of Ba atoms inside the AB-2LG induces a change in the Space group number from 164 (pure AB-2LG) to 156 (Ba-intercalated AB-2LG). Concurrently, we observed that the AB-2LG band structure exhibits a Dirac cone at the K-point, which is a characteristic signature of a semi-metallic character. By contrast, the electronic behavior of the barium-intercaled AB-2LG is found to be metallic. Also, we noticed that the confinement of Ba atoms into the AB-2LG shifts the Dirac point under the Fermi level. Additionally, upon examining the optical properties under the 001 and 100-polarization of the incident light, we found that all optical parameters of both under-investigated bidimensional materials exhibit an anisotropic character. Interestingly, under the 001-polarization, we observed that the intercalation of AB-2LG with Ba atoms reduces the optical absorption to zero in the visible region, and blueshifts are the absorption peak observed in the infrared region. Furthermore, in the case of 001-polarization, the presence of Ba atoms enhances the optical absorption in the 7-9 eV spectral range. However, the obtained data exhibit a remarkable decrease in the refractive index after the Ba intercalation process, for both considered polarization directions.
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| 2. |
- Chafai, A., et al.
(författare)
-
External electric field modulation of single-layer MoSe2 electronic and optical properties : A first-principles investigation
- 2023
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Ingår i: MICRO AND NANOSTRUCTURES. - : Elsevier. - 2773-0123. ; 182
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Tidskriftsartikel (refereegranskat)abstract
- A wisely applied external electric field could effectively develop the optoelectronic properties of single-layer materials. The optical and electronic characteristics of monolayer molybdenum diselenide (ML-MoSe2) are deeply studied by means of density functional computations (DFT) to pinpoint the effect of the out-of-plane applied electric field (F//Oz). In fact, variations in the applied electric field strength gradually increase the energy of the electronic band gap (Eg) from 1.44 eV at 0V/& ANGS; to 1.51 eV at & PLUSMN;0.6V/& ANGS;. We also probed a sharp drop in the energy gap at high intensities. However, dielectric function, reflectivity, and loss function are studied for unpolarized and polarized incident light. Interestingly, the 001-polarization of the incident light affects the dielectric function's magnitude and position; this effect is more emphasized in the presence of an electric field with positive strengths. Furthermore, we found that the applied negative/positive electric field enhances the UV-visible reflectivity. Also, blue shifts of the ML-MoSe2 optical properties spectrum appear when subjected to the 001-polarized incident light. However, the loss function exhibits a weak response to the applied F. Additionally, we obtain that the 001-light polarization improves a plasmonic peak around 100 nm. Our results will provide a new view to understanding the controllable optical and electronic properties of MoSe2 monolayer, which is valuable for the design of new optoelectronic and plasmonic devices under development.
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