This research work mainly focuses on various gate and channel engineering performed on typical tunnel field effect transistors (TFETs) at nano scale. This step-by-step development of typical nano device TFET model is showcased in this research work, in pursuit of better device performance. At first single gated homogenous dielectric i.e., SiO2 is used as oxide material, which further modified to dual gated heterogenous dielectric i.e. HfO2 – SiO2 combination in pursuit of better drive current (ION), and switching ratio (ION/IOFF). During this process simulation the intrinsic channel is developed as heterogeneous (InAs-Si) throughout the simulation. This results in considerable changes at surface potential distribution along the channel due to band-to-band-tunneling effect (BTBT). Secondly, this dual gated heterogeneous dielectric TFET is modified with 0-2 nm thin graphene layer, deployed over intrinsic channel. This nano-scaled graphene layer is introduced as nano-ribbon architecture, in order to reduce the tunable energy band gap. This expedites the BTBT tunneling across the junction and brings the turn on voltage (VON) much earlier, resulting fast digital switching. Lastly, this structure of TFET is further updated with dual metal, dual gated structure to investigate its ION/IOFF ratio and leakage current control. Silvaco TCAD is used to generate all related simulation work. Better drive current (ION) is achieved at 3.55 10 – 6 A/m with minimum leakage current (IOFF) of 2.16 10 – 16 A/m at 0.5 supply voltage (VDD) with minimum sub-threshold swing (SS) of 33.07 mV/decade.
In this work, the charge plasma (CP) technique is employed to induce carriers in the undoped channel region of a Silicon-on-Insulator (SOI) trigate MOSFET, eliminating the need for conventional doping and reducing variability at nanoscale dimensions. A metal layer with a suitably engineered work function (WK) is incorporated beneath the channel to electrostatically induce carriers in the intrinsic silicon region, enabling efficient channel formation. The device performance is analyzed in terms of carrier distribution, surface potential profile, current–voltage (I-V) characteristics, and transconductance, along with circuit-level evaluation through Voltage Transfer Characteristics (VTC) of inverter configurations and stability assessment of 6T SRAM cells for a channel length of 10 nm. Simulations are carried out using Sentaurus TCAD with advanced physical models, including the Lombardi mobility model to account for surface scattering, Shockley–Read–Hall (SRH) and Auger recombination models for carrier recombination, and the Density-Gradient model to capture quantum confinement effects. The incorporation of a high-k dielectric significantly reduces leakage current and enhances electrostatic control. It is observed that Drain-Induced Barrier Lowering (DIBL) can be effectively suppressed and tuned by optimizing the work function of the metal layer beneath the channel. As a result of the CP implementation, the proposed device demonstrates a 16 % improvement in drain current compared to the conventional SOI MOSFET. Furthermore, the implemented 6T SRAM circuits exhibit a 28 % enhancement in hold static noise margin, indicating improved stability and reliability, thereby making the proposed CP-based SOI trigate MOSFET a strong candidate for future low-power and high-performance applications.
Hexagonal patch antenna is therefore very different from conventional antennas. For next-generation cellular networks, a novel wideband hexagonal patch antenna concept is being presented. The structure is made up of microstrip rectangles and hexagonal structures, with a total area of 40 40 1.5 mm3. Hexagonal patch antenna is designed utilizing RT duroid substrate. An improved S11 of more than 15 dB at the resonating frequency is observed at 2.5 GHz (2.26-2.84 GHz). 3.6 dB gain has been observed at the resonant frequency of 2.5 GHz. Effective impedance matching has been achieved by using the microstrip transmission line edge feeding technology and DGS in the ground plane. Hexagonal patch antenna produces high-quality double-polarized radiation and wide bandwidth, designed and simulated in far-field radiating settings. A novel, lightweight, high gain and wide-bandwidth hexagonal patch antenna is also needed for the 5G smartphone antenna system. The hexagonal patch antenna is a better choice for future 5G cellular applications due to its performance and small architectures. The 5G wireless communication antenna is therefore very different from conventional antennas.
A van der Pauw-like nonlocal four-probe method is proposed and analyzed for studying the transverse electrical characteristics of non-uniform normal and superconducting materials. The conventional four-point probe design with four equally spaced, collinear electrodes, current applied through the outer pair, and voltage measured between the inner pair, assumes a uniform current distribution and isotropic conductivity. In contrast, the developed nonlocal electrical measurements take into account the heterogeneity through a generalized resistive network model with four contact pads: two current and voltage contacts on the top surface and two corresponding contacts on the bottom surface. The inclusion of scattering possibilities between all pairs of nodes, which in the classical domain can be replaced by corresponding resistances, leads to a realistic representation of the potential distribution and naturally explains the occurrence of both positive and negative nonlocal resistances observed experimentally. The temperature dependence of the nonlocal four-probe resistance is shown to be extremely sensitive to small differences in the superconducting parameters of layered structures. Distinctions in the critical temperature or transition width produce characteristic peak-dip features in the four-probe resistance, allowing direct identification of such inhomogeneities. The proposed nonlocal four-probe technique provides a simple yet powerful tool for resolving spatial variations in conductivity and superconducting transitions in thin films and multilayer heterostructures. Compatibility with existing measurement methods makes it a promising technique for both fundamental research and applied diagnostics in studies of the electronic properties of normal and superconducting materials.
Compact-sized circular patch antennas are used in satellites, mobile networks, radars, and other current and future wireless communications applications. In this paper, a low-profile crescent-shaped circular patch antenna with an inset feed for sub-6 GHz wire-free communication applications is examined. The basic design of a crescent-shaped circular patch antenna included a full ground. Following that, a defective ground structure is used to achieve a broader bandwidth. HFSS is used to examine a crescent-shaped microstrip circular patch antenna. A 3 dBi gain of 3.05 dB was achieved at 3.5 GHz, with a reflection coefficient of – 22.7 dB and a fractional bandwidth of 42.85 %. The crescent-shaped circular patch antenna contains a dimension of 31 28 1.6 mm3 and is printed on a FR4 epoxy dielectric material. The crescent-shaped CPA is simulated using FR4 epoxy as a dielectric with a loss tangent of 0.02, dielectric constant of 4.4, and thickness of 1.6 mm. PEC (perfect electric conducting) material is chosen as a conducting layer. Based on the simulation results, the circle patch antenna in the shape of a crescent is good for N77 and N78 sub-6GHz uses. The proposed antenna is optimized through a series of iterative procedures. The crescent-shaped CPA is composed of a concentric circular patch joined by a crescent-shaped patch. The proposed crescent-shaped CPA is simulated using the finite element method (HFSS). From the results it is a fact that the proposed crescent shaped antenna is well suited for sub-6GHz 5G applications.
This paper presents the results of the study of the electrical conductivity of structurally continuous thin films of CoNi and FeNi alloys in a wide range of thicknesses and concentrations of components. Alloy films with a thickness of 10-200 nm were obtained by condensation of evaporated initial massive binary alloys of CoNi and FeNi in a vacuum of 10 – 4 Pa. CoNi alloys were evaporated by electron beam method using an electron diode gun with a condensation rate of 0.5-1.5 nm/s. The purity of the initial metals Co and Ni was not less than 99.9%. The concentrations of components of CoNi alloy films varied in a wide range. FeNi alloy films were obtained as a result of evaporation with a 50N permafrost. Thermostabilizing of the electrophysical properties of alloy films was carried out during three heating-cooling cycles in the temperature range of 300-700 K. The dependences of the specific electrical resistance on the temperature of alloy films for the second and subsequent heating-cooling cycles practically coincide, which indicates complete stabilization of the properties of film samples after the second annealing cycle. An irreversible decrease in electrical resistance after heat treatment was experimentally revealed, which indicates ordering of the material structure. It was shown that the nature of changes in electrical resistance depends on both the thickness of the films and the ratio of components in the alloys. To interpret the obtained results, the Wend model of healing of defects in the crystalline structure of films was used, which allows us to explain the decrease in electrical resistance due to a decrease in the concentration of defects and an improvement in structural ordering. Based on this model, the spectra of defects in the crystalline structure in CoNi and FeNi alloy films were calculated.
This work presents the design and performance evaluation of a compact four-port mmwave MIMO microstrip patch antenna operating at 6.6 GHz, with substrate dimensions of 18.8 16.7 mm2, implemented on FR4 epoxy. Each patch element measures 9.2 7.1 mm2 and is optimized for high isolation and low return loss. The antenna is analyzed in terms of S-parameters, confirming return loss (S11 – 10 dB) and port-to-port isolation (S21, S31, etc. – 15 dB), ensuring minimal inter-element coupling for efficient MIMO operation. MIMO performance is assessed through computation of the Envelope Correlation Coefficient (ECC 0.01), Diversity Gain (DG ≈ 10 dB), and Total Active Reflection Coefficient (TARC – 10 dB), demonstrating high channel independence and diversity capability. The group delay is analyzed across the operational band, exhibiting a flat response that supports low-latency data transmission. The antenna’s radiation efficiency and gain are evaluated at 27 GHz to assess compatibility with mm Wave applications, with total efficiency exceeding 65% and gain values supporting practical integration in high-speed wireless systems. Additionally, the antenna integrates with the MQTT (Message Queuing Telemetry Transport) protocol stack to facilitate real-time performance monitoring and low-latency communication in IoT and 5G scenarios. The results confirm the suitability of the proposed antenna for compact, high-performance MIMO systems with IoT connectivity via MQTT.
This work introduces an innovative approach to optimizing the reflectivity of bi-isotropic multilayer mirrors at normal incidence through systematic manipulation of critical design parameters. The study demonstrates that high optical index contrast in material selection, combined with an increased number of bi-layers, significantly enhances reflection by creating multiple interfaces for electromagnetic interaction. By strategically adjusting layer thicknesses, favoring thinner high-index layers and thicker low-index layers, reflectivity can be substantially improved. A pivotal finding reveals that the ratio of bi-isotropic parameters (chirality to non-reciprocity) plays a crucial role in performance optimization, with lower ratios (below unity) achieving reflectivity values exceeding 92 % at λ = 500 nm, while higher ratios (above unity) progressively reduce reflectivity to approximately 68 %. A mathematical model relating reflectivity to parameter ratios is derived, providing a predictive tool for design optimization. This research leverages the unique electromagnetic properties of chiral and Tellegen bi-isotropic materials, exploring previously untapped characteristics to revolutionize modern optical devices. The originality lies in proposing novel strategies for applications in advanced optics and photonic crystals, unlocking new possibilities for optical communication, sensing technologies, and precision electromagnetic control systems. This comprehensive investigation offers fresh insights into how structural and parametric adjustments impact bi-isotropic mirrors, advancing their practical implementation in next-generation photonic technologies.
The article investigates the effect of annealing temperature and initial stoichiometry of Si oxide in a wide range on the phase composition of Si/SiOx nanocomposites formed by phase separation induced by high-temperature annealing. In this study, the appearance of internal stress hindering the phase separation process, is taken into account. The equilibrium stoichiometry of the Si oxide matrix, the relative amount of Si precipitated into the Si phase and the average precipitate size as functions of the specified parameters are modelled thermodynamically. The dependence of the percolation threshold of the Si nanoinclusions on the annealing temperature is determined. The obtained results are discussed comparing the contributions from different mechanisms during phase separation into the Gibbs free energy of Si/Si oxide systems.
This study introduces a compact, wideband quad-port MIMO antenna featuring a gear-shaped slot radiator integrated onto a 40 50 mm2 ITO-based dielectric substrate, engineered for 5G and WLAN applications below 6 GHz. The antenna is created through a series of design steps that start with a simple circular monopole, move on to partial ground modification, add multilayer slotting, and end with a gear-shaped form based on fractals. The optimized geometry, along with the ITO substrate's transparency and low loss properties, improves the flow of electrical current, making it easier to excite multiple modes and giving the system a wide range of impedance. The single-element prototype works in the frequency range of 2.1 to 5.9 GHz and has clear resonances at 3.2 and 4.5 GHz. The device has a peak gain of 3.1 to 4.2 dBi and a radiation efficiency of 86 to 91%. This means that it works well with a lot of different frequencies. To make the MIMO setup more isolated, corner parasitic patches are added. These patches stop surface-wave coupling without making the antenna footprint bigger. The suggested 2 2 MIMO architecture shows an isolation level of more than 18 dB and an envelope correlation coefficient (ECC) of less than 0.02, which guarantees better diversity performance. The proposed antenna is a strong candidate for next-generation portable 5G and WLAN communication systems owing to its compact dimensions, ITO composition, extensive frequency range, high efficiency, and superior isolation.
A study was conducted on the wear processes of nickel-based composite electrolytic coatings (CEC) under friction conditions without lubrication, taking into account changes in mechanical properties in the transition zone, the effect of diffusion chromium plating, and the dispersibility of the TiC carbide phase. The diffusion zone formed in the surface layer at the “coating-base” boundary ensured an increase in the adhesive strength of the CEC with the base and contributed to an improvement in the mechanical characteristics of the nickel matrix and the alloyed nickel matrix. The wear mechanisms were analyzed based on energy theory, according to which, in the contact zone, the energy of plastic deformation is converted into the energy of dislocations in the friction area, which causes the solid phase to crumble. The mechanism of destruction of the surface layers of the friction pair was evaluated based on the analysis of theoretical and experimental research data within the energy concept of the formation of wear particles in their near-surface zones. The influence of the mechanical properties of the material on the size of wear particles was shown. It has been established that the size of the spalling particles is determined by the elastic modulus of the substance, and their ability to penetrate the friction zone is determined by the specific cohesion energy.
This study is designed to examine the effect of pore size on the performance of aluminum matrix compo-sites reinforced with silicon carbide (SiC) particles that contain porosity. To accomplish this, we evaluate both constant and variable pore diameters, assuming a circular shape while preserving the same volume fraction. Finite element analysis is conducted on a square matrix reinforced with nine particles and subject-ed to a tensile test. The simulation utilizes a two-dimensional plane strain model, incorporating square, hexagonal, and random distributions of multiple particles. The findings reveal that, even with the existence of pores, the transfer of stress from the softer matrix to the reinforcement is still effective. Furthermore, it is observed that the composite's properties are increasingly influenced by porosity and pore size, especially as the pore diameter enlarges and the proximity to the particles diminishes.
The graphene field-effect transistor based on the reduced graphene oxide – zinc oxide – porous silicon – silicon substrate sandwich-like structure has been created for ionizing radiation detection. The hybrid structure was obtained as a result of sequential technological processes of photoelectrochemical formation of the nanostructured porous silicon, the electrochemical deposition of zinc oxide, application of a film-forming suspension of reduced graphene oxide nanoparticles, and subsequent drying at room temperature. Dependencies of the drain current on the drain-source voltage and gate voltage of the obtained field-effect transistor were analyzed. An increase in the resistance of the reduced graphene oxide film near the charge neutrality point caused by irradiation with the 226Ra isotope has been found. In addition, a displacement of the charge neutrality point in the direction of a lower gate voltage was observed. It has been established that ionizing radiation has a greater effect on the electronic component of the conductivity of the reduced graphene oxide film than on the hole component. An increase in the sensitivity of the created ionizing radiation detector due to the use of additional zinc oxide and porous silicon absorbing layers was established. Mechanisms of the influence of alpha and beta particles and gamma quanta on the electrical characteristics of the proposed sensor are discussed based on the analysis of the frequency dependences of the internal resistance and electrical capacitance, as well as the capacitance-voltage characteristics of the sandwich-like structure. The obtained results have a high potential to create a new type of small-sized dosimetric devices based on the graphene field-effect transistors using simple and low-cost techniques and materials.
Finite element analysis (FEA) has become a powerful alternative to experimental methods for investigating the pressure-dependent behavior of nanomaterials, offering high accuracy with reduced cost and complexity. In this work, a three-dimensional finite element model is developed to analyze and optimize the mechanical response of Fe2O3 nanomaterials under applied mechanical pressure. A cubic Fe2O3 crystal with dimensions of 100 nm 100 nm 100 nm is modeled, incorporating realistic material properties, boundary conditions, and mesh refinement strategies. Mechanical pressure ranging from 0 to 16 GPa is applied to evaluate volume ratio variation, stress distribution, and displacement characteristics. The results reveal a monotonic reduction in volume ratio with increasing pressure, indicating elastic compression and high structural stability. Stress analysis shows non-uniform distribution with localized concentration near boundary regions, while displacement remains minimal even at high pressure levels, confirming the stiffness of Fe2O3. Mesh convergence studies validate the numerical accuracy of the model. The optimized FEM results demonstrate close agreement with theoretical predictions and reported experimental trends, confirming the reliability of the simulation framework. This study highlights the effectiveness of FEM-based optimization for predicting pressure-dependent mechanical behavior of Fe2O3 nanomaterials and provides valuable insights for their application in pressure sensors, NEMS devices, and mechanically robust nano-scale system.
Theoretically, using two-current [1] and resistive models [2, 3], the dimensional effects (dependences of the magnetoresistive ratio on the thickness d2 of the top magnetic layer) of giant magnetoresistance in “symmetric” Fa > 1/S/Fa > 1 and “asymmetric” Fa1 > 1/S/Fa2 > 1 sandwiches have been investigated. It is shown that in regions of small (large) values of the thickness d2 of the top magnetic layer relative to the thickness d1 of the bottom magnetic layer, the giant magnetoresistance effect is negligible. This is due to the fact that when the inequalities d2 << d1 (d2 >> d1) hold, the specified effect is small due to the shunting of the resistance of the top layer (the resistance of the base layer) by the resistances of the base magnetic layer and the non-magnetic interlayer (the resistances of the top layer and the spacer). In the absence of the shunting effect, i.e., when the thickness of the top magnetic layer coincides with the total thickness of the spacer and the base magnetic layer, the magnetoresistive ratio reaches its maximum value. Analytical calculations of the parameters of electron spin-polarized transport were performed for both “symmetric” Fa > 1/S/Fa > 1 and “asymmetric” Fa1 > 1/S/Fa2 > 1 magnetically ordered sandwiches with ultrathin layers.
In this paper, a mathematical model based on the equivalent circuit (single-diode model) was used to study the electrical behavior of a GaAs/Ge single junction solar cell. In order to validate the suitability of this proposed model, nominal values provided by the manufacturer such as photocurrent (ISC), open circuit voltage (VOC), maximum power (Pmax), form factor (FF) and efficiency () were exploited. A comparison between the nominal static characteristics, current-voltage (I-V) and power-voltage (P-V), and those obtained through the proposed model of this solar cell showed that they were very identical. Based on this proposed model, the impact of irradiance and temperature on these static properties and on the various electrical parameters of this solar cell was investigated. This study demonstrated the suitability of this proposed model in exploring how the electrical behavior of this solar cell is affected by changes in illumination and temperature, respectively. Despite the simplicity of this proposed model, it presents good behavior and high performance, making it the most suitable mathematical model for studying single-junction solar cells based on GaAs/Ge semiconductor technology. MATLAB software was used to simulate the proposed model and to analyze the performance of this solar cell.
The results of investigations of the optical and electrical characteristics of green GaP light-emitting diodes (LEDs) grown by double liquid-phase epitaxy are presented. Low-temperature electroluminescence spectra in the wavelength range of 530 – 590 nm reveal a spectral structure with emission peaks at λ1 = 542 nm, λ2 = 554 nm, λ3 = 576 nm, and λ4 = 584 nm. Injection characteristics were obtained for the listed emission wavelengths. Comparative evaluations of the radiation resistance of emissions at λ1 = 542 nm and λ3 = 576 nm were carried out, as well as an analysis of the differential resistance values of the diodes in the regions of the current-voltage characteristics (CVCs) exhibiting positive and negative differential resistance. The effects of electron irradiation on the reverse currents of the LEDs were analyzed, in particular the expansion of the pre-breakdown region of the CVCs and the shift of the breakdown channel toward higher voltages. The work also includes results of studies on the recovery of the electrophysical characteristics of irradiated diodes induced by isochronal annealing.
The Aluminum Metal Matrix Composites (AMMCs) continue to attract substantial research interest for high-performance locomotive, aerospace, and defense structures due to their superior specific strength, stiffness, and tribological behavior. The present investigation aims to enhance the mechanical response of Al 7075 by hybrid augmentation with ceramic particulates. Boron carbide (B4C), known for its high hardness and modulus, was incorporated at a constant weight fraction, while zirconium dioxide (ZrO2), a toughening ceramic with high thermal stability, was introduced in varying weight percentages to evaluate its incremental contribution to composite performance. Hybrid composites were synthesized via the Stir Casting Method (SCM), selected for its capability to disperse ceramic reinforcements uniformly in the molten matrix through controlled vortex formation. Process parameters such as stirring temperature, stirring speed, and holding time were systematically regulated to minimize particle clustering, interfacial porosity, and wetting inconsistencies. Mechanical characterization comprised tensile testing, compression testing, and Brinell hardness evaluation in accordance with ASTM standards. Results indicated that hybrid reinforcement significantly enhances load-bearing capability and resistance to deformation. The composite containing Al 7075 + 3 wt. % B4C + 15 wt. % ZrO2 achieved the highest tensile strength of 192 MPa, compared to 137 MPa for the monolithic alloy, demonsrating a 40 % improvement. Similar trends were observed in compressive strength and hardness, attributed to particle-matrix interfacial strengthening, Orowan looping, dislocation pile-up at reinforcement boundaries, and microstructural refinement induced by ceramic additions. To identify the most influential processing parameters and optimize the mechanical response, the Taguchi L9 orthogonal array was employed. Signal-to-noise analysis confirmed that reinforcement ratio and stirring temperature were the dominant factors affecting property enhancement. The optimized parameter set yielded composites with superior mechanical performance and reduced variability. Overall, the findings establish that B4C-ZrO2 hybrid-reinforced Al 7075 composites fabricated via SCM are promising candidates for next-generation lightweight structural components demanding high strength, reliability, and thermal resilience.
Millimeter-wave (mmWave) communication is a fundamental enabler for next-generation wireless systems due to its capability to support ultra-high data rates and massive network capacity. However, the design of compact antennas operating at mmWave frequencies remains challenging because conventional microstrip patch antennas suffer from inherently narrow impedance bandwidth and limited radiation efficiency. This paper presents a compact wideband microstrip patch antenna operating at the 28-GHz band using a slot-engineered radiating structure combined with a partial ground plane. The antenna is fabricated on a Rogers RT5880 substrate (εr = 2.2, tanδ = 0.0009) with overall dimensions of 20 x 21 x 0.79 mm3. Bandwidth enhancement is achieved by introducing multiple resonant perturbations through strategically positioned slots, which effectively alter surface current distribution and reduce the antenna quality factor. The proposed antenna achieves a – 10 dB impedance bandwidth of 4.88 GHz (26.88-31.76 GHz), specifically covering n257 (26.5-29.5 GHz), n258 (24.25-27.5 GHz), and n261 (27.5-28.35 GHz) bands fully covering the targeted 28-GHz mmWave band. At the resonance frequency, the antenna demonstrates a return loss of – 46.91 dB, VSWR of 1.009, peak gain of 6.45 dB, and radiation efficiency exceeding 92 %. Electromagnetic analysis confirms that the slot configuration generates multiple coupled resonant modes, enabling broadband performance while preserving radiation stability. Comparative analysis with recently reported mmWave antennas demonstrates that the proposed design achieves a favorable trade-off between compact size, bandwidth, and radiation performance. These characteristics make the antenna a strong candidate for 5G, beyond-5G, and emerging 6G millimeter-wave communication systems.
The rapid advancement of the Internet of Things (IoT) and 5G communication systems necessitates antennas capable of delivering ultra-high data rates and wide bandwidths in the terahertz (THz) frequency band. This paper presents the design and development of a novel graphene-based triple-slotted hexagonal-shaped patch (TSHP) antenna intended for IoT applications in the THz frequency band. The proposed antenna features a compact hexagonal geometry with strategically incorporated slots and a partial ground structure to optimize key performance metrics, including bandwidth, gain, and radiation efficiency. The design process involved rigorous computational simulations to optimize the antenna structure for operation in the THz band, ensuring minimal loss and high precision. The CST Microwave Studio simulation environment is used to investigate the performance of the proposed antenna with an 80 60 m2 footprint. The simulation results demonstrate a broad bandwidth of 0.86 THz, a low return loss of – 36.76 dB, a high gain of 7.71 dB, and an efficiency of 81.59 %. The use of graphene as a conductive material enhances electrical and thermal performance, enabling the TSHP antenna to meet the stringent requirements of high-speed IoT networks. This work provides a robust foundation for developing efficient THz antennas, advancing the capabilities of next-generation IoT and 5G communication systems.
