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Our latest study builds upon our previous research on multi-wall carbon nanotubes (MWCNTs) by exploring the photonic responses of regularly β-aligned arrays of these nanotubes. Through extensive calculations using the Finite Difference Time Domain Method, we determined that MWCNT-based photonic crystals possess significant Bragg reflections of up to 80% without experiencing substantial attenuation, even at wavelengths as low as 17 nm. This discovery is of great significance, as traditional materials have not been able to scatter UV photons within this frequency range efficiently. Following extensive research, we analyzed various model parameters such as lattice periodicity, inner and outer radii of MWCNTs, and the polarization (TM or TE) and direction (Γ-X or Γ-M) of the incident wave. Our findings present promising implications for advancing ultra-highfrequency photon manipulation in EUV applications, with potential developments ranging from UV laser mirrors to EUV lithography lenses, and beyond to UV spectroscopy collimators. [ABSTRACT FROM AUTHOR]

We present a computational study on the electrical behavior of the field-effect transistor based on vertical graphene-hBN- χ 3 borophene heterostructure and vertical graphene nanoribbon-hBN- χ 3 borophene nanoribbon heterostructure. We use nonequilibrium the Green function formalism along with an atomistic tight-binding (TB) model. The TB parameters are calculated by fitting tight-binding band structure and first-principle results. Also, electrical characteristics of the device, such as ION/IOFF ratio, subthreshold swing, and intrinsic gate-delay time, are investigated. We show that the increase of the hBN layer number decreases subthreshold swing and degrades the intrinsic gate-delay time. The device allows current modulation 177 at room temperature for a 1.2 V gate-source bias voltage. [ABSTRACT FROM AUTHOR]

We present the results of a numerical study on the characteristics of MoS2-based field-effect photodetectors (FEPhDs). These FEPhDs consist of 12-nm-long and 1.42-nm (1.45-nm)-wide MoS2 armchair (zigzag)-nanoribbons (MoS2-A(Z)NRs), acting as channels connected to two semi-infinite graphene electrodes, serving as source and drain terminals to minimize the terminals' series resistances. The simulation method used here is the nonequilibrium Green's function formalism plus an atomistic tight-binding (TB) model. We employed the TB model to obtain characteristics like the density of states versus electron energy, current–voltage curve, and photocurrent versus photon wavelength (λ). For the latter, we consider illuminating the A(Z)NR channels with a broadband optical signal covering the λ = 330–830 nm range. Our simulations show that passivation of ANR edges with H2 and OH molecules reduces the semiconducting bandgap by ~ 28% (for H-ANR) and ~ 28.6% (for OH-ANR). The numerical results show that, among the three ANR channels, the optimum photoresponsivity of Rph ≈ 43.88 mA μW−1 belongs to the FEPhD with the MoS2-OH-ANR channel biased at VDS = 200 mV and VGS = 0, at λ ≈ 451 nm, independent of the illumination intensity. Among the three ZNR channels, the best photoresponsivity of Rph ~ 27.02 mA μW−1 belongs to the unpassivated channel under the same biasing condition but at λ ≈ 477 nm. The results also show that the optimum biasing condition differs from one FEPhD to another. The results show that the proposed MoS2-A(Z)NR-based FEPhDs can be promising candidates for nanoscale optoelectronic devices in the UV–Vis range. [ABSTRACT FROM AUTHOR]

We present a tight-binding (TB) model for describing the electronic properties of the free-standing χ3 and β12 borophenes via the Slater–Koster approach. This model is constructed through s, px, py, and pz orbitals for each boron atom. The optimal Hamiltonian plus the overlap matrix are calculated by fitting the results of the TB model and density functional theory calculations using the least-squares method and the Levenberg–Marquardt nonlinear fitting algorithm. Considering three nearest-neighbors and a non-orthogonal basis set, this TB model accurately describes energy bands around high-symmetry k-points. [ABSTRACT FROM AUTHOR]