Ab initio calculations of electronic and optical properties of BeO nanosheet

Valedbagi, Sh.; Jalilian, Jaafar; Elahi, Seyed Mohammad; Majidi, Soleyman; Fathalian, Ali; Dalouji, Vali

doi:10.1007/s13391-013-3097-z

Cited by 35 publications

(9 citation statements)

References 43 publications

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“…With this knowledge, we can exploit the moiré pattern to determine the h-BeO lattice constant with greater accuracy: with a moiré periodicity of 3.2 nm and the known lattice constant of 2.89 Å for Ag(111), one can deduce a lattice constant of 2.65 ± 0.01 Å for the h-BeO. This calculated lattice constant is consistent with the atomic resolution measurements, displaying a reduction in BeO bond length compared to bulk wurtzite structure, as theoretically predicted. ,,,− The decrease in lattice constant was previously theorized to stem from the graphitic Be–O bond having an increased covalent character, and as a result, the atoms move closer to increase the orbital overlap of nearest neighbors. ,, …”

Section: Resultssupporting

confidence: 83%

“…We next utilize scanning tunneling spectroscopy to study the electronic structure of the h-BeO. The differential conductance (d I /d V ) spectroscopy, representing the local density of states (LDOS), is shown in Figure a with spectra spanning 5 orders of magnitude in dynamic range and displayed in logarithmic scale, acquired at a set bias of 4.1 V. With such a large dynamic range, we can assign the location of the CBM at 3.0 ± 0.2 eV and VBM at −3.0 ± 0.2 eV, corresponding to a band gap of ∼6 eV, similar to the value of previous theoretical calculations. ,,− However, we note that it is difficult to assign the exact locations of the band edges with d I /d V spectroscopy alone. As discussed above, this explains why the layers resemble pristine Ag(111) at low sample bias (Figures b, b); within the band gap, the h-BeO does not contribute to the LDOS.…”

Section: Resultsmentioning

confidence: 99%

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Epitaxial Growth of Two-Dimensional Insulator Monolayer Honeycomb BeO

et al. 2021

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The emergence of two-dimensional (2D) materials launched a fascinating frontier of flatland electronics. Most crystalline atomic layer materials are based on layered van der Waals materials with weak interlayer bonding, which naturally leads to thermodynamically stable monolayers. We report the synthesis of a 2D insulator composed of a single atomic sheet of honeycomb structure BeO (h-BeO), although its bulk counterpart has a wurtzite structure. The h-BeO is grown by molecular beam epitaxy (MBE) on Ag(111) thin films that are also epitaxially grown on Si(111) wafers. Using scanning tunneling microscopy and spectroscopy (STM/S), the honeycomb BeO lattice constant is determined to be 2.65 Å with an insulating band gap of 6 eV. Our low-energy electron diffraction measurements indicate that the h-BeO forms a continuous layer with good crystallinity at the millimeter scale. Moiré pattern analysis shows the BeO honeycomb structure maintains long-range phase coherence in atomic registry even across Ag steps. We find that the interaction between the h-BeO layer and the Ag(111) substrate is weak by using STS and complementary density functional theory calculations. We not only demonstrate the feasibility of growing h-BeO monolayers by MBE, but also illustrate that the large-scale growth, weak substrate interactions, and long-range crystallinity make h-BeO an attractive candidate for future technological applications. More significantly, the ability to create a stable single-crystalline atomic sheet without a bulk layered counterpart is an intriguing approach to tailoring 2D electronic materials.

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Section: Resultssupporting

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Epitaxial Growth of Two-Dimensional Insulator Monolayer Honeycomb BeO

et al. 2021

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“…2(a) (light green arrow). We find that the properties of ε 2 for the BeO monolayer are completely different from the dielectric function for BeO bulk in wurtzite structure [37,38]. The difference between the monolayer and the wurtzite structure is due to differences in the Be-O hybridization.…”

Section: Nitrogen Doped Beo Monolayermentioning

confidence: 71%

Enhanced electronic and optical responses of Nitrogen- or Boron-doped BeO monolayer: First principle computation

Abdullah,

Rashid

et al. 2021

Preprint

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In this work, the electronic and optical properties of a Nitrogen (N) or a Boron (B) doped BeO monolayer are investigated in the framework of density functional theory. It is known that the band gap of a BeO monolayer is large leading to poor material for optoelectronic devices in a wide range of energy. Using substitutional N or B dopant atoms, we find that the band gap can be tuned and the optical properties can be improved. In the N(B)-doped BeO monolayer, the Fermi energy slightly crosses the valence(conduction) band forming a degenerate semiconductor structure. The N or B atoms thus generate new states around the Fermi energy increasing the optical conductivity in the visible light region. Furthermore, the influences of dopant atoms on the electronic structure, the stability, the dispersion energy, the density of states, and optical properties such as the plasmon frequency, the excitation spectra, the dielectric functions, the static dielectric constant, and the electron energy loss function are discussed for different directions of polarizations for the incoming electric field.

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“…The threshold energies and the peak positions tell us that the physical properties of pure BeO monolayer are different from the properties of BeO bulk in its wurtzite structure [20,44], which is due to the Be-O hybridization. In a BeO monolayer each atom (Be or O atoms) has three bonds with the nearest neighbor, but in the BeO wurtzite structure each atom is bonded with four other atoms.…”

Section: Optical Propertiesmentioning

confidence: 97%

“…x and an insulator for E ⊥ z. The optical spectra are anisotropic, and the static refractive index of the nanosheet structure is lower than that of the wurtzite structure [20]. The monolayer h-BeO exhibits a wide band gap due to the atomic electronegativity difference in the polar h-BeO.…”

Section: Introductionmentioning

confidence: 99%

High thermoelectric and optical conductivity driven by the interaction of Boron and Nitrogen dopant atoms with a 2D monolayer Beryllium Oxide

Abdullah,

Gudmundsson

2021

Preprint

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The electronic, thermal and optical properties of a monolayer BeO with Boron (B) and Nitrogen (N) co-dopant atoms are studied by means of a density functional theory computation. Our calculations reveal that BeO with BNcodopant atoms can give rise to more effective and outstanding performance for the thermal and optical responses. More significantly, the monolayer BeO with BN codopant atoms becomes a semiconductor with a direct band gap in comparison with the insulator behavior of pristine BeO. The particular attention of this work is paid to the influence of the atomic configuration and the interaction of the B and N dopant atoms with BeO. The interaction of the B and N atoms with the BeO monolayer diminishes degenerate energy states forming flat bands. It is also found that there is a strong attractive interaction between the O and N atoms forming a strong sigma bond breaking the symmetry of BeO structure. Consequently, the band gap is reduced leading to a semiconductor behavior with improved thermoelectric properties such as the Seebeck coefficient and the figure of merit. The reduced band gap and the flat bands induce a high optical responses such as the refractive index, the reflectivity and the optical conductivity in the visible light region. In addition, the anisotropy of a monolayer BeO with B and N atoms regarding different direction of electromagnetic polarization is presented. We anticipate that our results can be useful for design of both thermoelectric and optoelectronic devices.

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Ab initio calculations of electronic and optical properties of BeO nanosheet

Cited by 35 publications

References 43 publications

Epitaxial Growth of Two-Dimensional Insulator Monolayer Honeycomb BeO

Epitaxial Growth of Two-Dimensional Insulator Monolayer Honeycomb BeO

Enhanced electronic and optical responses of Nitrogen- or Boron-doped BeO monolayer: First principle computation

High thermoelectric and optical conductivity driven by the interaction of Boron and Nitrogen dopant atoms with a 2D monolayer Beryllium Oxide

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