International Journal of Nanoelectronics and Materials (IJNeaM)

Mutual Coupling Reduction between FSS Decoupling Structure and Nanoantenna Array-Elements in THz Multi-Band Plasmonic UM-MIMO

Wed, 09 Apr 2025 00:00:00 +0000

This study introduces a novel methodology for mitigating mutual coupling in Terahertz (THz) multi-band Ultra-Massive Multiple-Input Multiple-Output (UM-MIMO) systems, specifically focusing on plasmonic nanoantenna arrays. The primary objective is to reduce the interference between Frequency Selective Surface (FSS) decoupling structures and adjacent nanoantenna array elements, which is critical for optimizing THz communication system performance. The research involves the design and characterization of new FSS structures and nanoantenna array geometries, employing advanced materials to enhance mutual coupling reduction. By precisely tuning the array geometry and refining the FSS decoupling structure, the study achieves a significant reduction in mutual coupling, with a frequency offset improvement of 4.7% relative to baseline frequencies. Furthermore, the integration of the optimized nanoantenna array with the FSS structure yields substantial reductions in return loss, with S₁₁ and S₂₂ values reaching approximately -7 dB and -8 dB, respectively. The proposed design also demonstrates a compact and stable configuration, achieving a uniform mutual coupling reduction of approximately -22 dB and FSS decoupling structure. This work provides a robust and efficient solution for enhancing the performance and reliability of multi-band THz UM-MIMO systems.

Determination of mechanical and vibration properties of SiO001, SiO110, SiO111 nanowires using first principles approach

Wed, 16 Apr 2025 00:00:00 +0000

Nanowires play an important role in various applications, especially in exploring their electronic properties. While their mechanical properties have also demonstrated potential, they have not yet been fully theoretically investigated to determine their specific mechanical properties. The goal of this study is to investigate the mechanical properties of SiO nanowires using density functional theory and a first-principles approach. The mechanical properties along (001), (110), and (111) orientations were examined. The strains of 0.1164 × 10-5, 0.12 × 10-5, and 0.115 × 10-5 for each of the three orientations, with moduli of 149.5 GPa, 75.5 GPa, and 85.1 GPa, were found. The total energies along the same orientations (001), (110), and (111) were found to be -1.33, -1.35, and -1.37 eV, respectively. The corresponding Debye temperatures were 676.14 K, 454.70 K, and 616.26 K. The values of Frantsevich's ratios of 0.38, 0.22, and 0.36 along with Poisson's ratios of 0.33, 0.40, and 0.34 confirmed that the nanowires in all crystal directions are ductile. These results demonstrate that the first-principles approaches utilised in this study to study SiO nanowires' characteristics were able to capture the exact behavior of the nanowire parameters.

A 25 GHz Voltage-controlled oscillator (VCO) for automotive collision avoidance radar

Wed, 23 Apr 2025 00:00:00 +0000

This paper presents the design and implementation of a 25 GHz voltage-controlled oscillator (VCO) tailored for automotive collision avoidance radar systems. The VCO, a crucial component of the synthesizer, is essential for generating variable frequencies. This study focuses on addressing the challenges of high-power consumption and phase noise, which are critical factors in the performance of radar systems. The simulations were conducted using LTspice to evaluate the VCO's performance in terms of phase noise and power consumption, utilizing 0.18 µm CMOS technology. The proposed VCO employs a modified current-reuse configuration to enhance power efficiency and incorporates resistive and inductive source degeneration techniques to minimize phase noise. The results demonstrate that the VCO achieves a tuning range of 25.34–25.94 GHz, with an impressive phase noise of -156.61 dBc/Hz at a 1 MHz offset and -157.43 dBc/Hz at a 10 MHz offset for the resistive degeneration configuration. The inductive degeneration configuration shows a phase noise of -156.562 dBc/Hz at a 1 MHz offset and -157.431 dBc/Hz at a 10 MHz offset. Additionally, the power consumption is measured at 207.4 mW for the resistive configuration and 208.39 mW for the inductive configuration. These findings indicate that the proposed VCO design meets the stringent requirements of low power consumption and low phase noise and provides a reliable solution for implementing efficient radar systems in automotive applications.

Characterization of carbon black and graphite filled epoxy conductive ink via green solvent method

Wed, 23 Apr 2025 00:00:00 +0000

Conductive ink is gaining attention in the electronics industry due to its affordability, simplicity, and environmentally friendly properties. This study aimed to analyze a conductive ink made with Carbon Black (CB) and Graphite (G) as fillers, with epoxy resin as the binder and a green co-solvent of ethanol and distilled water. Various characterization techniques were used to examine the fillers. X-ray diffraction (XRD) revealed that CB exhibited an amorphous region at the (002) peak around 21.1°, while G showed distinct peaks at 26.5° and 54.4°, indicating a well-ordered graphitic structure. UV-Vis analysis showed that both CB and G interacted with the epoxy matrix, with an absorption peak in the 270-280 nm range corresponding to π–π* transitions. Fourier-transform infrared (FTIR) spectroscopy confirmed this interaction, with the presence of hydroxyl groups (2800–3500 cm⁻¹) and carboxyl group vibrations at 1241 cm⁻¹, indicating bonding between the polymer and filler. The dispersion of the fillers in the epoxy matrix was examined using Field Emission Scanning Electron Microscope (FESEM), which also assessed agglomeration. The ink's conductivity was tested according to ASTM F390 standards, with optimal CB loading at 4% achieving a conductivity of 4.49 × 10⁻⁵ S/m and optimal G loading at 3% yielding a conductivity of 7.14 × 10⁻⁵ S/m. These results indicate that G-based conductive ink with 3% loading performs better than CB-based ink for printed electronics applications.

A full range fully analytical drain current model of double gate junctionless field effect transistor with triangle shaped spacer

Anjanmani Baro, Kaushik Chandra Deva Sarma — Wed, 23 Apr 2025 00:00:00 +0000

A full range and fully analytical model for the drain current of a symmetric double gate junctionless field effect transistor with a spacer of triangular shape is presented in the paper. The model is valid in the complete range of operation of the device, i.e., all four modes of operation namely- subthreshold, bulk current, flatband and accumulation modes. The approach to obtain the model is channel resistance based. The resistance of the channel of the device has been obtained from charge enclosed within it. The resistances of the model vary in different modes. Therefore, four expressions are obtained for four different modes of operation namely sub threshold, bulk current, flatband and accumulation. The model is said to be analytical in nature as each mode is represented by one single expression without the involvement of any numerical integration. Quantum confinement effect has also been considered in the model. The model has been validated with the help of simulation results from Technology Computer Aided Design (TCAD) device simulator. For the purpose of validation, the model is compared with simulation results as well as experimental results from existing literature. The average deviation from experimental results is 1.425% and the maximum deviation is 1.7%.

Performance of electrochemical amperometric sensor based on annealed and non-annealed PANI-Ag-Pt nanocomposite thin films for E. coli detection

Thu, 24 Apr 2025 00:00:00 +0000

Herein, we report the fabrication of polyaniline with Ag-Pt alloy nanocomposite thin films based amperometric E. coli sensor. The effects of annealing at 300^oC during the synthesis of PANI-Ag-Pt nanocomposite thin films are studied. XRD, AFM, FESEM and FTIR spectroscopy analyses are conducted to characterize the films. Sensor performance is investigated by the I-V characteristic of PANI-Ag-Pt films with and without the presence of E. coli. From XRD analysis, annealed films have larger crystallite sizes than non-annealed films. AFM results indicate that annealed films have lower surface roughness but larger grain size than non-annealed films. FESEM images show Ag-Pt nanorods with sizes of 200-300 nm for non-annealed films and Ag-Pt nanocubes with sizes around 100-550 nm for annealed films. The composition of PANI-Ag_0.2-Pt_0.8 nanocomposite thin film has higher conductivity and performed the maximum sensitivity upon E. coli presence. The sensitivity of annealed PANI-Ag-Pt films is higher than non-annealed PANI-Ag-Pt films.

The influence of midfield applying fly ash for the mechanical arts, and flame resistance of polymer composite

Thu, 24 Apr 2025 00:00:00 +0000

Polyurethane (PU) grouting material has been widely employed because of its critical function in safeguarding people and property from fires and the burning of polymeric composites. The material's poor flame retardancy and high cost, however, have limited its adoption. Here, in order to reduce the cost of manufacturing and prevent dirt formation from fly ash (FA), we partially replace the conventional filler in PU grouting materials with modified surface fly ash (FA), a byproduct extracted from the ash waste of gas combustion in domestic electric generators in Iraq. The work in this paper includes two types of fillers FA and Zirconium dioxide (ZrO₂). In the first group the surface modified FA(PU/FA) and (PU/ZrO₂). The mixture was prepared separately at 25°C by hand layup method. The second group hybrid composite was prepared, the PU/ZrO₂ at fixed ratio of ZrO₂(1%) were mixed with various loading percent (1%,2%,3%) of FA at room temperature curing also. The composite was characterized using SEM, FTIR and the fire frustration tests included Limited Oxygen Index (L.O.I), maximum flame height, and the moment of ignition time (flame exposure time) and thermal behave hardness of prepared snips using DSC were scrupulous. The outcome expressed that (PU/FA1/Z1) with 1wt.% of each filler had the maximum fire retardancy concluded from weight loss test but at (loading 1%) were obtained the maximum value of hardness (95.4). The fusion was recorded the maximum heat for 1%FA. The final outcomes rating sure on the ability of using faint loadings of prepared FA to mend the fire retardancy, thermal and mechanical properties successfully

Simulation and modeling of gallium nitride high-electron mobility transistors for non-alloyed ohmic contacts

Thu, 24 Apr 2025 00:00:00 +0000

The advantages of gallium nitride (GaN) high-electron mobility transistors, such as concentrated channel electron density, superior electron mobility, and high breakdown voltage, present an opportunity to replace silicon-based devices from modern power conversion systems in the near future. The development of low-resistance ohmic contacts in aluminium gallium nitride (AlGaN)-based GaN devices is crucial for predicting their performance. However, only limited studies have employed technology computer-aided design (TCAD) software to investigate contact resistance in GaN devices and to develop strategies for minimizing contact resistivity. Furthermore, the ohmic contact is able to be achieved only based on different configurations of metal stacks with annealing. This study, using Silvaco TCAD Atlas, first modeled contact resistance in a vertical structure and later extended the study to a lateral structure, which is more feasible for physical manufacturing. The investigation focused on various n++ regions with different doping levels beneath the metal to determine the best optimization for ohmic contact. The result revealed that reducing contact resistivity saturated (1 × 10−6 Ω/cm2) at a thickness of 18 nm for the heavily doped layer (≥ 1 × 1019 cm−3), beyond which no significant decrease in contact resistivity was observed for varying doping levels in n++ layers. This study demonstrates that including a heavily doped layer between the contact and semiconductor surfaces results in the ohmic behaviour emergence in metal contacts.