Journal of Computational Electronics最新文献

Several D–π–A compounds (CTFM1-CTFM7) were developed to evaluate their linear and nonlinear optical (NLO) properties. A thieno[2,3-b]indole-based chromophore (CTFM) was selected to design new derivatives by incorporating various electron-donating (D) groups. The designed compounds consisted of dithieno[3,2-b:2′,3′-d]thiophene as the π-spacer and 2-(3-cyano-4-methyl-5-phenyl-5-(trifluoromethyl)furan-2(5-H)-ylidene)malononitrile as the acceptor unit along with a range of strong donors. Density functional theory (DFT) and time-dependent DFT (TD-DFT) were employed to investigate their geometrical and optoelectronic properties utilizing the conductor-like polarizable continuum model (CPCM) to simulate solvent effects in the chloroform medium. Additionally, their optical properties were investigated by calculating the excitation energies and simulating the UV-Visible spectra at the B3LYP/6-311G(d,p) level. The outcomes showed significantly reduced E_gap values (1.801–3.228 eV) and bathochromic shifts (551.408–709.901 nm) in the designed chromophores. Particularly, CTFM6 exhibited the least E_gap (1.801 eV) and highest absorption wavelength (709.901 nm) was noted for CTFM7. Further, the hyper-conjugation and intramolecular interactions were visualized using the natural bond orbitals (NBOs) analysis. The NLO properties showed prominent results for CTFM7 compound i.e., < α >  = 1.77 × 10⁻²² esu, β_total = 3.33 × 10⁻²⁷ esu and γ_total = 3.06 × 10⁻³² esu. Similarly, frequency-dependent electro-optic Pockels effect (EOPE) i.e., β(− ω,ω,0) and electro-optic Kerr effect (EOKO) i.e., γ(− ω,ω,0,0) also showed the highest values for CTFM7 as 6.25 × 10⁻²⁵ and 5.51 × 10⁻³⁰ esu, respectively. Overall, the designed chromophores demonstrated significant NLO characteristics validating their potential as promising candidates for the optoelectronic applications.

We present a study of the digital and analog/RF performances of nanosheet field-effect transistors (NSFETs) for different source–drain (S/D) and bottom isolation configurations. The bottom isolation techniques evaluated include the punch-through stopper (PTS) and bottom dielectric isolation (BDI). Regarding S/D contact methodologies, three configurations were examined: top, wrapped-around (WAC), and metal sidewall (MSW). The combination of bottom isolation techniques and S/D configurations led to eight device variants. For each structural variation, the parasitic components are extracted, and the circuit performance is evaluated. For each structure, the digital circuit performance is evaluated by investigating the delay of a CMOS inverter. The RF performance was also assessed by investigating the cutoff frequency (F_t), the maximum frequency of oscillation (F), and the RF parameters for each structure considering the back-end of line (BEOL) parasitics. The BDI scheme demonstrated improved performance over the conventional PTS by an average of 5% and 9% for digital and RF applications, respectively. Combining BDI with MSW and WAC schemes significantly enhances the performance. For instance, the maximum performance gain over conventional PTS and top-contact schemes was 32% for digital applications, while F_t improved by 8% and F improved by 13%. MSW outperformed WAC by an average of 2%.

We present a comparative investigation of one-dimensional photonic crystal (1D PC) and quasi-periodic photonic crystal (1D QPC) structures—specifically Fibonacci and Thue-Morse sequences—for biosensing applications using various blood components as defect layers. The transmission spectra for platelets, plasma, white blood cells (WBC), and hemoglobin (HB) were investigated for both healthy and infected states. The study highlights a distinct resonance wavelength shift in each structure corresponding to changes in refractive index, enabling the detection of health conditions. Among the three configurations, the Fibonacci-based 1D QPC exhibited the best sensing performance, with the highest sensitivity and figure of merit (FOM). For instance, it achieved a FOM of 220.17 /RIU for platelets, 275.25 /RIU for plasma, 266.77 /RIU for WBCs, and 232.42 /RIU for HB—significantly outperforming in case of the Fibonacci sequence structure. The Thue-Morse structure showed moderate improvements over the periodic case, but the Fibonacci design delivered the sharpest resonance modes and clearest distinction between healthy and infected samples. These results demonstrate the potential of quasi-periodic Fibonacci photonic structures for highly sensitive, label-free biosensing applications in medical diagnostics.

The precise control of electromagnetic wave behavior is essential for the development of next-generation photonic and communication devices. Metamaterials enable advanced wave manipulation through their unique electromagnetic properties. Among their key building blocks, metallic nanowires have been designed to dilute plasma frequency, a concept validated at microwave frequencies. Existing nanowire models face limitations; the quasi-static voltage-current models apply only to dipole-dominant nanoparticles, while wave impedance methods require infinite series expansion. These constraints highlight the need for a computationally efficient and physically intuitive modeling approach. This work introduces a cylindrical wave impedance framework at optical frequencies, deriving impedance expressions that simplify the dominant-mode resonance analysis under TE polarization by mapping it to a linear circuit model. The dominant mode is validated through simulations and Mie theory comparisons, ensuring accuracy. The proposed compact and intuitive model enhances understanding of wave-nanowire interactions, aiding the design of plasmonic and metamaterial-based applications. It also opens new avenues for the analytical treatment of complex nanostructures in both research and practical device engineering.

In recent decades, there has been significant interest in finding negative electrode materials that offer excellent reversibility, low open circuit voltages, high specific capacity, and rapid charge–discharge rates. This inclusive innovation study examines the suitability of a T-BN monolayer as negative electrode material for Na-ion batteries (SIBs) applying first-principles computations. The impressive flexibility of T-BN enables it to exhibit strong reversibility when faced with volume expansion resulting from full adsorption. Furthermore, when Na is adsorbed onto the T-BN monolayer, the layer exhibits metallic characteristics, highlighting an exceptional electrical conductivity. Moreover, the T-BN monolayer exhibits a combination of features including a suitable average open-circuit voltage (OCV, 0.26 V), remarkable specific capacity (839.51 mA h g⁻¹), low diffusion energy barrier (37 eV), and minimal change in lattice constants (2.78%). With these outstanding characteristics in mind, we anticipate that T-BN has promise to serve as a favorable negative electrode material for SIBs.

We present a compact in-fiber polarization beam splitter (PBS) implemented in a gold-coated dual-core photonic crystal fiber (DC-PCF), using finite element method (FEM). The octagonally arranged DC-PCF achieves enhanced birefringence through optimized structural design. Gold layers integrated within the two large air holes induce surface plasmon resonance (SPR), which modulates the optical response at the edges of the operational band and enhances polarization splitting efficiency. Numerical analysis shows that when the lattice gap Λ = 1.6 μm, diameters d₁ = 1.2 μm, d₂ = 0.5 μm, d₃ = 2.1 μm, d₄ = 0.7 μm, and a gold layer thickness of t = 50 nm, this PBS achieves a coupling length ratio (CLR) of 0.5 at 1.55 μm. It exhibits a shortest splitting length of 220 μm and a maximum extinction ratio (ER) of -133 dB over an operating bandwidth of 140 nm. The fabrication process and experimental setup are analyzed. It is worth anticipating that this polarizer will emerge as a crucial signal processing component in photonic integrated systems, driving the continuous advancement of communication systems and information technology.

In this work, an interpretable hybrid modeling framework is developed that integrates physics-based TCAD simulations, compact Verilog-A implementation, and graph neural network (GNN) analysis to investigate nanoscale Junctionless Gate-All-Around (JLGAA) FETs for ultra-low-power current mirror circuits. The proposed multi-scale methodology couples Silvaco TCAD data with a calibrated Verilog-A compact model, enabling accurate and efficient circuit-level evaluation in the Cadence Spectre environment. The compact model reproduces TCAD characteristics with less than 2.5% deviation, while achieving a > 1000 × reduction in simulation time compared with full 3-D TCAD analysis. An interpretable GNN-based deep learning framework predicts circuit performance metrics, including current accuracy, output resistance, and power consumption, with a mean absolute error below 4% across 900 simulation cases. SHapley Additive exPlanations (SHAP) reveal that channel doping and gate length dominate current matching and energy efficiency. The proposed hybrid TCAD–Verilog-A–GNN methodology provides a transparent, accurate, and computationally efficient pathway for the design and optimization of next-generation ultra-low-power nanoelectronic circuits.

This study aims to enhance the performance of dithienosilole-based non-fullerene acceptors (NFAs) for organic solar cells (OSCs) through strategic end-capped modifications. Eleven novel NFAs (D1–D11) were theoretically designed by substituting the cyano groups of the reference molecule (BCNDTS, R) with various electron-withdrawing units. Their optoelectronic and photophysical properties were systematically investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) at the PBE1PBE/6-31G(d) level. Among all the scrutinized structures, D10 showed the most remarkable outcomes, such as the lowest band gap (E_g = 1.96 eV), the greatest electron affinity (E_A = 3.35 eV), the highest λ_max (773 nm in gaseous and 836 nm in dichloromethane), and the lowest excitation energy (E_x = 1.60 eV in gaseous and 1.48 eV in dichloromethane). D9 also exhibited considerable enhancements in different aspects, such as a planar structure, the highest light harvesting efficiency (LHE = 0.990), and a narrow bandgap (E_g = 2.04 eV). The electron donor molecule PTB7TH was used to calculate the open-circuit voltage (Voc) of the model molecule and D1–D11. It was found that end-capped tailoring has a significant effect on the open-circuit voltage. In order to assess the charge transfer ability of the designed acceptors, we presented the HOMO and LUMO orbitals of the complex D9-PTB7Th. It was found out that all the tailored compounds, particularly D10 and D9, could be advantageous in the manufacturing of advanced NFAs for next-generation photovoltaic technologies especially D10 and D9.

Graphical abstract

Graphene nanostructures (GNSs) exhibit unique electronic and magnetic properties dependent on their shape and size. This research investigates the face index, a topological descriptor derived from chemical graph theory, as a means to characterize the structural topology of three distinct regular convex polygons: triangles, hexagonal, and rhombus-shaped GNSs, which are the most simple high-symmetry convex structures that can be ideally cut out of a graphene layer. We calculate the face index for these three geometries using graph theoretical methods. The results offer quantitative insights into the structure of these nanomaterials and provide a valuable contribution toward understanding structure–property relationships in graphene-based systems.

The electronic structure and optical properties of the photodetector based on the vertical TeSe₂/GaSe van der Waals heterostructure (vdWH) have been investigated by way of the first-principles calculations. The obtained results indicate that the dynamically stable TeSe₂/GaSe vdWH exhibits an indirect band gap of 0.63 eV and a type-I band alignment. A semiconductor-to-metal transition can be realized when the compressive strain exceeds − 4.4%, and the band alignment of the system should transform from type-I to type-II at the regime of 1.1% to 3.7% in-plane biaxial tensile strain. Compared to the TeSe₂ and GaSe monolayers, the TeSe₂/GaSe vdWH photodetector exhibits maximum absorption coefficient of ~ 25% in the visible range. The maximum photocurrent of the proposed TeSe₂/GaSe vdWH photodetector reaches 0.97 ({text{a}}_{0}^{2}/text{photon}) at the photon energy of 1.8 eV while the extinction ratio achieves a maximum value of 33.2 at the photon energy of 2.0 eV. The proposed photodetector from the vertical TeSe₂/GaSe vdWH may shed some light on the realization of high-performance photodetector applications.