Journal of Computational Electronics最新文献

We use an improved shift operator finite-difference time-domain (ISO-FDTD) algorithm, previously proposed by others, to further process more complex dielectric functions including critical models and several higher-order Lorentz models that we fitted ourselves. These function models have a total of 6–8 sub-terms, and each sub-term consists of two complex poles (Lorentz model). This work supports the universal applicability of the ISO-FDTD algorithm for processing higher-order complex dispersive materials. We applied this ISO-FDTD algorithm in split-field FDTD (SF-FDTD) to simulate dispersion media under oblique incidence. The simulation results agree well with the analytical solutions. Thus, this approach provides researchers with an alternative option apart from auxiliary differential equations (ADE) or piecewise linear recursive convolution (PLRC) methods when processing high-order dispersive media in SF-FDTD.

In this article, we illustrate the working principle of optoelectronic mixing for uni-traveling-carrier photodetector (UTC-PD). As a result of the combined influence of local oscillators (LO) and bias modulation signals (RF), the velocity and concentration of photogenerated electrons in the depletion region exhibit mixing components with frequencies of (|{f}_{LO}pm {f}_{RF}|). The optoelectronic mixing signal is primarily generated by these two components, and its peak value is determined by the concentration of photogenerated electron. Moreover, the cliff layer can greatly enhance the output power of the mixed frequency signal, since it allows more photogenerated electrons to be transmitted to the depletion region.

This paper investigates the performance of a low-profile 8 × 8 multi-input-multi-output (MIMO) antenna with zero ground clearance, designed using an intelligent antenna recommender system. A dissimilar antenna pair is employed to achieve multi-band resonance and enhance isolation for sub-6G mobile communication. The primary antenna is a loop antenna resonating at n77, n79, and n46 bands, designed with the aid of a model developed using a support vector machine (SVM). The auxiliary antenna is a modified monopole resonating at n78 and n79 bands to minimize the antenna footprint on mobile devices. An eight-antenna MIMO array is fabricated, and measured results demonstrate that the proposed antenna has a reflection coefficient of less than − 10 dB at 3.5, 3.7, 4.5, and 5.2 GHz, with diversity gain and isolation greater than 9 dBi and 15 dB, respectively. SAR analysis conducted on a human head model shows a maximum SAR value of less than 1.6 W/kg at all sub-6G bands, compliant with FCC standards. The proposed MIMO antenna offers a viable solution, even when integrated with a battery and display, without occupying internal space within a mobile phone.

We present the results of an investigation of the optical characteristics of pristine and CO₂-adsorbed MoSe₂ monolayers with (without) an external electric field. The optical parameters of interest are the absorption coefficient (α), reflectance (R_f), refractive index (n), and photoconductivity (σ). The impact of an external electric field (−2 × 10⁸ V/cm) on the optical behavior of the MoSe₂ monolayer is systematically investigated. The results show the peaks of the real component ((varepsilon_{1})) of the dielectric function for both pristine and CO₂-adsorbed MoSe₂ monolayers in the energy range of 2–3 eV. The imaginary part ((varepsilon_{2})) of the dielectric function exhibits a shift toward the visible region from the ultraviolet (UV) region, in which CO₂ is adsorbed, and this shift increases toward the visible region with the application of an external electric field. Analysis of the absorption index, refractive index, and reflectance reveals that the peaks are aligned in the visible range for both the pristine MoSe₂ and CO₂-adsorbed MoSe₂ monolayers, with (without) an external electric field. The shifts of these peaks follow a similar trend as the imaginary part of the dielectric constant. Lastly, this study provides additional insight into the photo-detection performance parameters (internal quantum efficiency [IQE], external quantum efficiency [EQE], light extraction efficiency [LEE], and responsivity) for both pristine and CO₂-adsorbed MoSe₂ monolayers, considering the presence or absence of an external field.

This research presents a simulating electrohydrodynamically (EHD) inkjet-printed memristors in LTspice environment, a popular tool for analog circuit simulation. EHD printing technique is used as one of low cost fabrication technique for fabricate flexible thin films and memristors with high precision and resolution in a scale of nanometers. Memristors are cutting-edge components for AI hardware, and they can be fabricated through various methods, including traditional semiconductor processes and printed electronics techniques. However, printed electronics fabrication based for memristor modeling accurately remains a challenge. This paper introduces a mathematical model specifically for (EHD) inkjet-printed memristors, employing empirical mathematics to ensure compatibility with LTspice. While the modeling of printed electronic devices still in the early stage—to the knowledge of the authors-this paper will discuss for the first time mathematical and Spice modeling for printed memristor. The model is validated against actual memristors with a sandwiched structure ((text {Ag/ZrO}_{2}/text {Ag})), showing acceptable error percentage. It involves modifying an existing memristor model by incorporating a function that reflects the characteristics of the EHD printing process. This function is designed to capture the impact of the printing technique on various device parameters, such as width and length, with a focus on accurately modeling the width in the LTspice environment. This paper presents a developed LTspice model based on the proposed empirical mathematical model. The results are based on different sizes: 40 nm, 120 nm, 680 nm, respectively.

AlGaN/GaN HEMT-based gated-anode diode (GAD) has been investigated with a physics-based TCAD simulation tool to understand its electrical transport characteristics. The simulation study predicted that the GAD exhibited low turn-on voltage ((V_{text {on}}) = + 0.77 V) over a conventional Schottky barrier diode (SBD). However, the GAD suffers from low breakdown voltage ((V_{text {BD}})) because of strong electric field crowding at the gate edge. On the other hand, a δ-doped GaN cap (δ-DGC) layer has been able to spread out the electric field along the channel. With such modification in the epi-structure, a (V_{text {BD}}) of ~ 335 V could be achieved with the gated-anode-to-cathode distance ((L_{text {gac}})) of 10 μm. TCAD-based RF simulation and small-signal S-parameter analysis were carried out to evaluate the expected RF performance of the GADs. From the transient response of the extracted small-signal equivalent circuit parameters, the cut-off frequency ((f_{text {c}})) of the GADs with δ-DGC layer was 35.6 GHz at the exact turn-on condition ((V_{text {on}})) of the device.

Capacitive pressure sensors have the advantages of high accuracy and sensitivity compared to piezoresistive pressure sensors, but have serious nonlinearity problems. Although the touch mode capacitive pressure-sensitive structure has improved this issue, it has introduced a large hysteresis. To restrain this effect, a line-touch mode capacitive MEMS pressure-sensitive structure is proposed. A recess on the lower electrode plate of this structure makes the contact between the upper and lower electrode plates appears as the line-touch, and the touched area is almost zero, which can greatly minimize the hysteresis caused by the electrode plate contact. Analysis shows that the linear response range of this pressure-sensitive structure can be expanded several times more than that of the touch mode capacitive pressure-sensitive structure, while the nonlinearity is significantly reduced.

In the present paper, a simple qualitative model is proposed to study the effect of dimension and crystal structure on the energy band gap of semiconducting nanomaterials. The energy band gap variation is studied for nanoparticles, nanowires and thin films. The model takes into account the crystal structure and to incorporate the effect of crystal structure on energy band gap, lattice packing fraction is included in the mathematical formulation. The model does not involve any approximation or adjustable parameter. The study on nanosized semiconductors is performed. The model results depict the increase in the energy bandgap of nanosized semiconductors with reduction in size to nanoscale. Based on dimensionality, increment in energy band gap of spherical nanoparticles (NP’s) is more than that in cylindrical nanowires (NW’s) and thin films. The model results are found in good agreement with compared experimental and stimulated data. Drastic increase in energy band gap in nano-semiconductor of diameter or height less than 10 nm is due to the quantum confinement of charge carriers with increase in the surface area/volume ratio. With reduction in size of the Nano semiconductor, increase in the Band gap is observed leading to the blue shift. The energy band gap dependence on size in the nanorange has opened the possibility of tuning the energy band gap of the nanomaterials and use them in the opto-electronic devices.

In this work, doped and dopant-free carrier-selective passivating contacts have been incorporated in Interdigitated Back Contact solar cells. TCAD simulation study was done to check the performance of an IBC-SHJ (Silicon Hetero-Junction) and IBC-POLO (POLy-silicon on Oxide as seen in TOPCon) cell structures for both p and n-type wafers. The IBC-POLO structure was also repeated with HfO₂ and ZrO₂ over electron transport and hole transport layers, respectively. Simulation study was done by replacing the doped silicon layers with dopant-free Transition Metal Oxides (TMOs). NiO was used as a dopant-free hole-selective contact, whereas Nb₂O₅ was used a dopant-free electron-selective contact. The fabrication of these materials is non-hazardous and at low temperatures due to which they are preferable over the doped Si layers that require toxic gases like phosphine, diborane, etc. and may also require high temperatures. For example, poly-Si layer applied in IBC-POLO requires an annealing temperature of over 800 °C; similarly, the diffusion of Front Surface Field (FSF) layer in normal IBC cells also requires the same high temperature. Temperature variation was done on these structures to check the dependence of solar PV parameters of each IBC structure on different temperatures. Same variation was checked with minority carrier lifetime of the silicon wafer.

This paper presents and investigates a new architecture of a computational cell based on nanoparticles of the phase-change material Ge₂Sb₂Te₅. Such a cell is a chaotic array of nanoparticles deposited between closely spaced electrical contacts. The state of such a structure is determined by the resistance of the nanoparticle array, which depends on the phase state of each particle of the material. Simulation results show that the proposed structure has a number of electrical states switching features that cannot be achieved using a thin film architecture. The proposed architecture allows for smoother and more controlled switching of the resistance by electrical pulses. Simulation of the evolution of the cell state using complex control actions showed that the proposed structure can behave as an artificial convolutional neuron with horizontal connections and also as a multi-level memory cell. In addition, the proposed design is technologically simple to achieve and inexpensive to manufacture.