Journal of Computational Electronics最新文献

Special tran function theory (STFT) is a powerful nonlinear problem-solving tool. In this paper, four different nonlinear power engineering problems in the field of induction machines, power inductors, perovskite solar cells, and supercapacitors are represented via the same transcendental equation. Furthermore, the analytical solution of the derived transcendental equation is expressed by using the STFT. Comparisons of the accuracy of the presented solutions with corresponding solutions determined with numerical calculation for all observed power engineering problems are also presented. It is shown that the proposed analytical solution is applicable, simple to implement, highly accurate and low-time consuming. Furthermore, in the mathematical sense, the structures of the final expressions for all observed variables in all observed problems are simpler than literature-known analytical solutions. The Mathematica codes for different STFT solutions are given as an appendix of this paper.

Developing flexible, extremely sensitive strain sensors with a broad operating range is critical for applications such as healthcare, human motion, human–machine interface, and robotics. The COMSOL Multiphysics Finite Element Modeling software has been used to simulate serpentine geometry CNT-silicon-based flexible piezo-resistive (PZR) strain sensors with various sensor line thicknesses (LT), line widths (LW), pitches (P), and structures (Str whereby Str1 is P in the x-direction, and Str2 is P in the y-direction). Their effect on mechanical and piezo-resistive characteristics for strain ranging from 0 to 100% has been studied. The responses of the proposed modeled sensors have been simulated and analyzed in terms of numerous variables, including maximum displacement, von Mises stress, and sensor sensitivity. The simulation study concluded that for the Str1 structure, the PZR strain sensor with P (0.5 mm), LT (0.5 mm), and LW (1.5 mm) had the highest sensitivity (GF 120.50), while the PZR strain sensor with P (0.5 mm), LT (0.5 mm), and LW (1.5 mm) had the lowest sensitivity (GF 48.99). It is also found that the sensitivity of the Str1 PZR strain sensors rises when LW increases while P and LT decrease. Furthermore, the PZR strain sensor with P (0.5 mm), LT (0.5 mm), and LW (1 mm) of structure Str2 has the highest sensitivity (GF 165.95), and the PZR strain sensor with P (1.5 mm), LT (0.5 mm) and LW (0.5 mm) showed the lowest sensitivity (GF 161.62) among all the Str2 sensors, and it is revealed that the sensitivity increases with the decrease of P and LT while the effect of LT is not apparent. As a result, the modeled sensor can be employed as a highly sensitive PZR strain sensor with an excellent capability to monitor a wide range of human motions over the range of 0–100% strain.

A thin film of transition metal oxide (TMO) layer forms a heterojunction configuration with silicon (Si) via dopant-free fabrication process. However, excellent hole selective contact performance of TMO/n-Si heterojunction necessitates a stringent alignment of energy levels. Herein, we studied the level matching strategy of TMO/n-Si heterojunction with four parameters including conduction band (E_C), bandgap (E_g), Fermi level (E_F) and interface trap concentration (N_t). It is found that the electron affinity (E_a) of TMO determines the relative position of the energy level, and increasing the E_a can increase the open-circuit voltage (V_OC) from 426.0 to 742.5 mV. In addition, the energy level bending of the interface can be adjusted by the relative E_F position of TMO and n-Si to improve the carrier separation efficiency to increase the short-circuit current density (J_SC). Meanwhile, the higher N_t is beneficial to the carrier tunneling transport in the case of E_C of TMO being smaller than that of n-Si, which enhances the energy level bending of the interface and improves the solar cells performance. Finally, the MoO_x/n-Si heterojunction solar cell is optimized to obtained the power conversion efficiency (PCE) of 21.87%.

Abstract

In this paper, we investigate the total absorption coefficient, refractive index change coefficient, second harmonic generation and third harmonic generation of quantum dots in a weakly coupled quantum plasma under the effects of an Aharonov–Bohm flux field, topological defect and uniform magnetic field. The calculations are carried out via the Pekar variational method and compact density matrix approach. By solving the Schrodinger equation, the energy levels are derived. Then, using the obtained energy eigenvalues, we deduce the optical properties of the considered system. Our results show that with significant variations in the magnitudes of the parameters, either a redshift or a blueshift and maximum and minimum resonance appear.

Innovations in deep learning technology have recently focused on photonics as a computing medium. Integrating an electronic and photonic approach is the main focus of this work utilizing various photonic architectures for machine learning applications. The speed, power, and reduced footprint of these photonic hardware accelerators (HA) are expected to greatly enhance inference. In this work, we propose a hybrid design of an electronic and photonic integrated circuit (EPIC) hardware accelerator (EPICHA), an electronic–photonic framework that uses architecture-level integrations for better performance. The proposed EPICHA has a systematic structure of reconfigurable directional couplers (RDCs) to build a scalable, efficient machine learning accelerator for inference applications. In the simulation framework, the input and output layers of a fully integrated photonic neural network use the same integrated photodetector and RDC technology as the activation function. Our system only compromises on latency because of the electro–optical conversion process and the hand-off between the electronic and photonic domains. Insertion losses in photonic components have a small negative impact on accuracy when using more deep learning stages. Our proposed EPICHA utilizes coherent operation, and hence uses a single wavelength of λ = 1550 nm. We used the interoperability feature of the Ansys Lumerical MODE, DEVICE, and INTERCONNECT tools for component modeling in the photonic and electrical domain, and circuit-level simulation using S-parameters with MATLAB. The electronic component acts as the controller, which generates the required analog voltage control signals for each RDC present in the photonic processing engine. We employed MathWorks MATLAB 2022b for the classification of handwritten digits from the MNIST database; the proposed coherent EPICHA achieved accuracy of 94%.

This paper presents a deterministic approach for solving the Boltzmann transport equation (BTE) together with the Poisson equation (PE) for III-V semiconductor devices with a three-dimensional ({textbf {k}})-space. The BTE is stabilized using Godunov’s scheme, whose linearity in the distribution function simplifies the application of the Newton–Raphson method to the coupled discrete BTE and PE. The formulation of the discrete equations ensures the nonnegativity of the distribution function regardless of the scattering rate, which can include the Pauli exclusion principle, and exhibits excellent numerical stability under steady state as well as transient conditions. In the latter case, both implicit and explicit time integration methods can be used and even slow processes (e.g., recombination) can be handled using this approach. In addition, the direct solution of the BTE can be easily extended to the small-signal case for arbitrary frequencies. Exemplary BTE results are shown for a GaAs ({textrm{N}}^{+}{textrm{NN}}^{+})-structure, revealing, inter alia, that the approximations of the drift-diffusion model can fail for large built-in fields in III-V devices.

For single-electron transfer in common-gate multidot devices, the arrangement of stability regions along the gate voltage (V_g) axis is important because single-electron transfer occurs around the overlap of stability regions. The stability regions along the V_g axis are well known to have periodicity when the device has an integer ratio of gate capacitances (C_g). However, the arrangement rule for the real C_g ratio is unclear. In this paper, stability regions for quadruple-dot devices with symmetric C_g are exhaustively examined. The arrangement of stability regions along the V_g axis is drawn as a map of the real C_g ratio in a newly proposed diagram. Here, the arrangement for a particular C_g ratio is drawn along a straight line that passes through the origin and has a slope depending on the C_g ratio. In the diagram, stability regions are arranged two-dimensionally, and the abovementioned periodicity for integer C_g ratios clearly appears. How neighboring stability regions interrelate with each other in the diagram is mathematically examined and described in detail. Next, the sequences of tunneling events around the overlap of stability regions are investigated, and eight kinds of tunneling sequences for single-electron transfer are determined.

Abstract

Flexible wearable pressure sensors with high sensitivity have a wide range of applications in the field of healthcare monitoring, e-skin technology, robotic limbs, and other human–machine interaction under low pressures. For very low pressures, a sensor with high sensitivity and bulky, expensive measuring equipment is required to obtain the output signal. The incorporation of a micro-pyramidal porous dielectric section can considerably enhance the sensitivity of the capacitance-based pressure sensor. This article has employed a finite element method-based three-dimensional simulation to assess the performance of the porous microstructured capacitive pressure sensor (pmcps). The numerical results revealed a high level of agreement with the experimental data. To simplify the design and fabrication of the sensor with optimal performance, the effects of parameters such as sensor dielectric constant, dielectric layer porosity, base length, tip width, height, and inter-microstructural spacing of porous micro-pyramids were investigated using the response surface methodology. Sensitivity analysis showed that the tip width of the micro-pyramid has the greatest effect on sensor sensitivity and the least effect on the initial capacitance. Finally, equations were proposed for predicting the initial capacitance and sensor sensitivity based on the geometric parameters of the porous micro-pyramid and intrinsic properties of the dielectric section using three-dimensional finite element simulation to facilitate the ability to predict the fabrication and design process of the pmcps and optimize its performance for different applications.

The variation in bandgap energy with decreased size and varying composition of alloys has attracted the attention of researchers over the past few decades. In the present paper, a simple unified model is presented to study the impact of alloying on the bandgap energy of ternary semiconducting compounds with varying composition. The energy bandgap is determined for semiconducting homogeneous nano-compounds with zinc-blende and wurtzite structure, including Zn_xCd_1−xS, Zn_xCd_1−xSe, Cd(S)_x(Se)_1−x, and Cd(Se)_x(Te)_1−x. The model does not involve any adjustable parameters. The study provides insight into the impact of size, dimension, and composition on the energy bandgap of the material and the possibility of tuning the optical properties of semiconducting compounds by alloying, as alloyed compounds could be more stable and have higher luminescence than single semiconducting nanocrystal with a narrower energy bandgap. The model predictions are in good accord with the available experimental and simulated data.