Journal of Computational Electronics最新文献

Volatile organic compound (VOC) gases can act as biomarkers for early-stage cancer detection. For this purpose, the detection of VOCs at low ppm levels is critical. To achieve this goal, this study presents a surface acoustic wave (SAW)-based VOC sensor with a composite nanostructure consisting of carbon nanotubes (CNT) and molybdenum disulfide (MoS₂) as sensing material. The gas-sensing performance of two models based on CNT and CNT-MoS₂ sensing layers was investigated for ten types of VOCs at levels of 10–100 ppm at room temperature. The 2D SAW sensor model was designed and analyzed using the finite-element method (FEM)-based COMSOL Multiphysics 6.0 software. These two-port SAW devices were constructed using a 128° Y-cut LiNbO₃ substrate with aluminum as interdigital transducers (IDTs). In the first model (M1), CNT was used as a sensing layer with a resonant frequency of 905.27 MHz, and the second model (M2) used a CNT-MoS₂ sensing layer with a resonant frequency of 901.89 MHz. The shift in the resonant frequencies and their respective sensitivity with the presence of VOC gases was calculated. The greatest shift in frequency among gases in both models was found for 2-propanol, with 724.1 Hz/ppm for M1 and 1605.5 Hz/ppm for M2. In addition, the composite device M2 displayed superior selectivity (1630.1 Hz/ppm) to ethanol. The higher sensitivity of M2 may be due to the efficient adsorption of VOC gas molecules on the surface of the CNT-MoS₂ nanocomposite, which has a larger specific surface area and provides more active sites, resulting in a greater change in the device resonant frequency due to the mass loading effect.

A rectenna structure based on a potentially printable V-shaped nanoantenna (VSNA) design is introduced and numerically analyzed. The characteristics of the VSNA structure have been investigated through the electric field enhancement and radiation efficiency used as figures of merit to evaluate its performance. A comparative study has been performed between the VSNA and a conventional dipole THz antenna based on the same dimension constraints. Therefore, the VSNA has shown better and more localized field enhancement at the arm tips. Furthermore, an optimization process has been carried out to maximize the electric field at the resonance frequency (28.3 THz). The suggested design offers more than 300% improvement in electric field confinement compared to a conventional dipole antenna at 28.3 THz. This enhancement is attributed to the tip-to-tip geometry, leading to a highly localized field at the tip. Further, the optimized VSNA design is employed to form a rectenna structure by inserting an ultra-thin insulator layer between the tips of the antenna arms. The reported rectenna structure increases total efficiency from 11 to 26.58%, with a 141% improvement over previously reported work. Beyond the potentialities presented by the proposed design, its simplicity makes it manufacturable for efficient energy harvesting applications. Finally, the metal–insulator–metal (MIM) diode rectification capabilities have been investigated through a quantum mechanical simulator (built on MATLAB software) with aluminum oxide (Al₂O₃) as an insulator sandwiched between gold (Au) and silver (Ag). The suggested MIM diode (Au/Al₂O₃/Ag) offers a zero–bias responsivity of 0.93 A/W, which is higher than the previous work based on Al₂O₃ which was 0.5 A/W.

The voltage–current characteristics of solar cell models, regardless of the equivalent circuits used, are nonlinear functions that can be mathematically represented by the g-function. Computational modeling plays a key role in solving such complex functions, enabling accurate simulations and efficient solutions that are essential for optimizing solar cell performance. This paper first provides a comprehensive overview and comparative evaluation of several iterative methods used to solve the g-function. Next, the accuracy of these iterative methods across both positive and negative values of the functional argument is assessed. The number of iterations required to achieve the desired accuracy is then analyzed, along with the influence of accuracy on the number of iterations. Additionally, the computation times of all the observed methods are examined, along with the impacts of the initial values on the required number of iterations. Finally, the paper demonstrates the application of the proposed iterative methods for voltage calculations within a single-diode model of solar cells. The findings suggest that the Halley iterative method demonstrates superior efficiency, requiring fewer iterations for accurate results and lower computation time, whereas the Newton and Ostrowski methods yield similar performance. MATLAB codes for each iterative method discussed are provided, ensuring their applicability for addressing various engineering challenges related to the g-function.

In this paper, the optoelectronic performance of monolayer 1T-PtSe₂ materials under doping and biaxial tensile strain are investigated, with a focus on the impact of doping with second-period non-metal elements on the optoelectronic properties of the materials. By calculating the formation energy of each dopant system, it was found that the stability of each dopant system is in the order of Ne < F < N < O. The band gap of O-doped system is reduced, and the valence band of the N-doped system crosses the Fermi energy level. The forbidden bandwidth of the monolayer 1T-PtSe₂ decreases with increasing applied biaxial strain and reaches a minimum when the strain reaches − 8%, and the nature of the bandgap remains as an indirect bandgap. When the photon energy reaches 4 eV, the absorption peak of the N-doped system is significantly enhanced. The compressive strain resulted in an elevated absorption peak in the monolayer 1T-PtSe₂ system. This result provides a valuable reference for the potential application of this material in microelectronics and optics.

In this paper, based on exponentially distributed trap density of states (DOS) for grain boundary, a solution to effective mobility (μ_eff) is derived. Within the model, an effective width of grain boundary (GB) depletion region (L_GB.eff) and drain induced grain barrier lowering effect on GB barrier height (ψ_B), is considered. The μ_eff model is then verified with μ_eff extracted from simulation. To this end, a computer aided design simulation is calibrated against the experimental data and μ_eff is then calculated from the simulated channel current. The μ_eff model is compared with calculated μ_eff to validate the model and a good agreement between them is achieved. In addition, we also investigate the dependence of μ_eff on GB DOS parameters and device temperature. The same validation process is also performed at various GB locations and angles to analyze the effect of GB shape on μ_eff.

The growing interest in tuning the conduction properties of single-molecule junctions has drawn attention to studying their interaction with incident electromagnetic fields. The theoretical complexity of this problem necessitates the use of nonequilibrium statistical mechanics combined with quantum electrodynamics, leading to extremely time-consuming simulations. In this work, we propose a computationally efficient algorithm, which combines EE-BESD—an efficient and effective simulator of current–voltage characteristics in dark conditions—with approximated models for light interaction, specifically the Tien-Gordon and Floquet models. We validate EE-BESD-PAT through comparison with ab initio calculations and experimental data from the literature. Our computational model demonstrates good agreement with both experimental and density functional theory calculations, demonstrating that the proposed method is a promising computationally efficient tool without sacrificing accuracy.

The quantum-dot cellular automata (QCA) technology is considered as a possible nanoelectronic technology for future computing facilities. The leading role of QCA wires makes it preferable for serial data transfer/processing. Many modern computer applications require direct processing of decimal information without representation and conversion errors. The main purpose of the research is to design a novel QCA serial decimal digit multiplier. A QCA wire can be considered as a virtual tape with written binary symbols. The designed multiplier uses the Turing machine run-time multiple tapes reconfiguration to multiply two decimal digits encoded in the 5-bit Johnson–Mobius code. The proposed multiplier has successfully passed verification. In comparison with possible QCA BCD multipliers, it shows significant hardware simplification.

Metasurfaces can flexibly regulate terahertz wave, but most of reported results are limited to single polarized terahertz wavefront manipulation. In this article, the propose metasurface can manipulate linearly polarized and circularly polarized terahertz waves. It consists of five metal layers (namely metal rectangular bars, metal rings, two orthogonal metal gratings, and I-shaped metal layers) separated by four polyimide dielectric layers. For circularly polarized wave incidence, the metasurface generates vortex beams with topological charges of l =  ± 1 and l =  ± 2 at frequency of 1.2 THz. In addition, the metasurface achieves “T” shaped near-field image at 0.931 THz. Under linearly polarized wave incidence, the metasurface produces polarization conversion with a conversion ratio over 98% within the frequency range of 0.6–0.8 THz. The proposed structure has potential application prospects in terahertz wave multi-polarized manipulation in future terahertz wireless communication.

In light of the continuously rising demand for portable handheld devices in day-to-day life and in specific applications such as biomedical systems (blood pressure monitors, pacemakers, and hearing aids), stable digital systems with low area and power consumption are required. Static random-access memory (SRAM) is a fundamental component of digital systems, and hence stable and efficient design of SRAM is critical. This paper reports on the stability and reliability of a SRAM device designed using a gate-stack junctionless double-gate transistor (GS-JLDGT). The proposed GS-JLDGT is used to implement a six-transistor (6T) SRAM, and the GS-JLDGT structure is then modified by adding an oxide layer in the middle and utilized to design a 3T SRAM. As a result, the area occupied by the proposed 3T SRAM is reduced by almost half as compared to a conventional 6T SRAM layout. The reliability assessment of the designed SRAM is carried out by the inclusion of interface trap charges at the oxide–semiconductor interface. The results show that the presence of the interface trap charges leads to degradation in the voltage transfer curve (VTC) and hence significant deviations in various stability parameters, including the retention noise margin (RNM), static noise margin (SNM), static voltage noise margin (SVNM), static current noise margin (SINM), write trip voltage (WTV), and write trip current (WTI) of the device. In addition, the impact of temperature variation along with trap charges is investigated with respect to the stability of the GS-JLDGT-based 6T SRAM. The results indicate that as the temperature increases, distortion due to trap charges also increases significantly.

Nanotechnology has revolutionized circuit design by enabling highly efficient and compact components. Central to this innovation is the two-input NOR logic gate, a universal element in logic circuits that facilitates the construction of diverse logic configurations. Its versatility plays a pivotal role in digital logic design, particularly within the realm of molecular transistor technology, where miniaturization and efficiency are paramount. In this paper, a novel device is presented based on the Oligo (phenylene ethynylene) (OPE) molecule. OPE molecules offers significant advantages in digital circuits due to their superior electronic properties, nanoscale size, self-assembling capabilities, and tunable characteristics. By leveraging this intriguing feature of the proposed dual-gate molecular transistor, a two-input NOR logic gate is realized. The study employs advanced simulation techniques, including Non-Equilibrium Green’s Function formalism and density functional theory, to model quantum transport properties. Insights gained from these simulations elucidate the performance and reliability of molecular transistors under varying operational conditions, advancing our understanding of their potential in future nanoelectronics applications.