Band 114, Heft 7-8

Crystalline silicon solar cells have been the workhorse of the Solar Photovoltaic industry, contributing to >90% of the total installations. The fabrication of solar cells involves multi-process steps i.e. chemical treatment, diffusion, passivation and metallization. Among these process steps of solar cell manufacturing, metallization is the most critical one since it not only influences cell performance but also the cost of manufacturing to a great extent. A proper metallization process essentially helps in reduction of various electrical and optical losses. A lot of research is being carried out on various metallization technologies to arrive at an efficient, cost-effective solution for contact formation. Screen printing, flexographic printing, laser metal sintering and recently developed 3D printing are some of the technologies of interest in this field. While 3D printing, laser metal sintering, etc. are still at lab level, flexographic and gravure printing are in search of a suitable paste which can make the technology production-worthy. It is the screen-printed technology of solar cells that currently dominates the commercial market because of its low production cost and process simplicity. Amongst the several technologies that have been developed till date for cell metallization, the screen-printing technology promises to be the most reliable, rugged and production-worthy technology. In this paper, different metallization technologies viz. screen printing (conventional, knotless), stencil printing, light induced plating, metal sintering, flexographic printing, aerosol printing etc. used for contact formation in high efficiency silicon solar cells have been reviewed.

Nonlinear optical studies of organic compounds have been widely conducted because of its great scope in molecular engineering. In the present work, we have chosen an organic compound acetylsalicylic acid due to its non-centrosymmetric structure and presence of extended conjugated π -system. Nonlinear optical response of the probe system has been explored computationally by using density functional theory with B3LYP/6-311G++(d,p) basis set. To explore the nonlinear optical response, Mulliken charge analysis, Raman, UV–vis, nuclear magnetic resonance, molecular electrostatic potential analysis, polarizability, first order hyperpolarizability etc., have been applied for the probe molecule. Observed high value of dipole moment of optimized structure, charge transfer in the system, high Raman activity, and high value of polarizability, first order hyperpolarizability validate the strong candidature of acetylsalicylic acid to be used as a nonlinear optical active material in the future.

Theoretical and experimental studies are performed on the new organic–inorganic hybrid molecule N‐(2,6‐dimethylphenyl)‐1‐piperazineacetamide. The vibrational spectra of the molecule are characterized using FT‐IR and FT‐Raman in the range 4000–600 cm −1 and 4000–100 cm −1 , respectively. Density functional theory with B3LYP/3‐21G and B3LYP/cc‐pVDZ basis sets is used to calculate energy, geometrical structure, and vibrational modes of stretching, bending, and torsion. The VEDA software Autodock Vina revealed a good binding is employed to calculate the detailed vibrational assignments. The theoretical and experimental vibrational data are compared to support the present study. Density functional theory is used to calculate thermodynamic parameters (heat capacity, entropy, and enthalpy) and nonlinear optical properties. The software Gaussian09W and Gaussview 6.0 are used for theoretical calculations. Molecular docking studies are carried out to investigate the effect of the titled molecule against various proteins such as SARS‐CoV‐2 that affect the immune system in humans. Chemical shifts are identified using carbon and proton NMR. Non‐covalent interactions are studied using a reduced density gradient. The chemical reactivity and selectivity for a local reactivity site are analyzed with the help of Fukui functions.

In the present work, we explored the nonlinear optical properties of imidazole-2-carboxaldehyde, which is an aromatic derivative of imidazole. Optimization has been performed for imidazole-2-carboxaldehyde using density functional theory with a B3LYP/6-311G basis set. To check the possible charge transfer, Mulliken charge analysis and molecular electrostatic potential analysis was performed. The chemical reactivity of the probe molecule was investigated by calculating different frontier molecular orbital parameters such that energy gap, ionization potential, electron affinity, chemical potential, electronegativity, softness, and hardness. Raman, Fourier transform infrared, and nuclear magnetic resonance analysis was also performed to study vibrational properties and UV–vis was performed to study the electronic properties of the compound. A high value of dipole moment ( μ total ), polarizability ( α ), first-order hyperpolarizability (β ), and Raman activity validates the NLO behavior of the compound. Thus, the performed computational study validates a strong candidature of imidazole-2-carboxaldehyde to be used as a non-linear optically active material in the future.

To enhance the sensing performance of a four-layer planar polymer optical waveguide, an adlayer of tungsten disulfide material is introduced. Also, the proposed waveguide is used to demonstrate theoretically the detection of uric acid concentration in blood or urine. The heterostructure of two-dimensional WS 2 offers excellent dry lubricity with respect to any other 2D substance, such as graphite or molybdenum disulfide. The proposed waveguide is analyzed using the common path Mach–Zehnder interferometric method. The dispersion characteristic i.e., the effective refractive indices and thickness of proposed waveguide is plotted for a particular wavelength range to optimize the thickness of film layer. The difference in propagation constant and output interference signal for changing the cover medium is calculated. Using the output interference signal, the phase sensitivity 213 degree/RIU is obtained in the proposed waveguide. The maximum obtained sensitivity, limit of detection and limit of quantification for uric acid concentration in the proposed waveguide structure is 6.86 × 10 −2  degree mM −1 , 0.061 mM and 0.203 mM, respectively.

We analyzed the linear mode conversion of incident terahertz (THz) radiation into THz surface plasmon waves (SPWs) over a surface of graphene deposited on the rippled dielectric substrate. Obliquely incident p-polarized laser light imparts oscillatory velocity to the electrons in ripple layer regime. Electron oscillatory velocity beats with ripple surface density to produce a linear current density. We examine the tunable response of mode conversion of incident terahertz radiation with respect to change in Fermi energy of graphene and incident angle. A suitable surface ripple wave number resonantly drives the THz SPW. We observe the THz SPW generation tunability with respect to Fermi energy of graphene and incident angle. The amplitude of THz SPW is increased by lowering the Fermi energy of the graphene sheet.

We propose a mechanism for the generation of second harmonic terahertz surface plasmon waves by incident terahertz electromagnetic radiation ( ω , k 0 ) over a graphene surface deposited on the rippled dielectric substrate (SiO 2 ). A p-polarized THz radiation incident obliquely on the graphene surface exerts a nonlinear ponderomotive force on free electrons in the rippled regime. This nonlinear ponderomotive force imparts oscillatory velocity to the electrons at frequency 2 ω . Second harmonic oscillatory velocity couples with the modulated electron density and generates a nonlinear current density that drives second harmonic terahertz surface plasmon waves. Rippled surface provides an extra wave number for the phase matching condition to produce resonantly second harmonic at frequency 2 ω and wavenumber (2 k 0 z + q ). We examine the tunable response of second harmonic terahertz surface plasmon waves with respect to change in Fermi energy of graphene and laser incident angle. Second harmonic amplitude gets higher values by lowering the Fermi energy ( E F ) and increasing incident angle.

Sol–gel derived Sm–Co co-substituted BiFeO 3 ceramics (Bi 1– x SmFe 1– x Co x O 3 with x = 0.0, 0.01, 0.02 and 0.03; named as BFO, BSFCO-1, BSFCO-2 and BSFCO-3, respectively) were investigated for structural, vibrational, magnetic and optical properties. Distorted perovskite rhombohedral structure with R 3 c crystal symmetry has been established in X-ray diffraction (XRD) patterns analysis by Rietveld refinement and detailed structural parameters like lattice constants, unit cell volume, bond angles, bond length etc. have been evaluated. Raman spectra further confirmed typical rhombohedral structure of BiFeO 3 by exhibiting 13 clear Raman active phonon (9E + 4A) modes along with second order modes in the wave number range 50–1500 cm −1 . Fourier Transform Infrared (FTIR) spectra showed the presence of Fe–O and Bi–O bands and the calculated Fe–O bond length was in good agreement with that obtained from Rietveld analysis. Room temperature magnetization versus magnetic field ( M–H ) measurement using Vibrating Sample Magnetometer (VSM) showed enhancement of ferromagnetic ordering parameters with increasing Sm–Co content in BiFeO 3 samples. The maximum magnetization values increased from 0.237 emu g −1 for BFO sample to 1.167 emu g −1 for BSFCO-3 sample along with increase in remnant magnetization values. The optical property of Bi 1– x SmFe 1– x Co x O 3 samples was investigated by estimating the energy band gap using UV–Visible spectroscopy. The calculated values of energy band gap were varied in the range 2.46 eV–1.81 eV indicating tuning of energy band gap with Sm–Co co-substitution in BiFeO 3 sample.

In this work, Sr and Ti doped BiFeO 3 (bismuth ferrite) compositions with dopant x = 0.00 and x = 0.10 have been synthesized by conventional solid-state-reaction method. X-ray diffraction patterns of the pure and Sr and Ti modified BiFeO 3 samples with x = 0.10 have shown single phase formation. Rietveld refinement of X-ray diffraction data for both the samples has revealed Rhombohedral structural symmetry with R 3 c space group. Fourier-transform infrared spectroscopy spectra, recorded in the range 1000–400 cm −1 show shift in the position of a broad hump at higher wave number side with x which may be attributed to the stretching of Bi–O and Fe–O bonds due to doping. UV–visible spectra (ultraviolet-visible spectroscopy) in the range 300–800 nm have revealed a slight increase in the band gap with substitution.

A comparative study on the manifestation of rare earth ions substitution induced alteration in structure, magnetic and optical properties of BiFeO 3 nanoparticles was done. Sol-gel technique was employed to synthesize Bi 1 −x R x FeO 3 ( x = 0.05 and 0.10; R : Ce 3+ , Sm 3+ and Dy 3+ ) nanoparticles. X-ray diffraction patterns and Raman spectra analysis confirmed substitution driven structural phase transformation from distorted rhombohedral structure to orthorhombic structure for x = 0.10 samples. The enhanced magnetic properties with weak ferromagnetic behaviour were observed with increasing concentration of rare earth ions in BiFeO 3 nanoparticles. The improved magnetic characteristics are attributed to many factors such as the uncompensated surface spins in nanoparticles, breaking of spin cycloid with R 3+ ions substitution and super exchange interaction between R 3+ and Fe 3+ ions. The maximum magnetization values of 1.77 emu g −1 , 1.87 emu g −1 and 5.5 emu g −1 were observed for x = 0.10 samples with Ce 3+ , Sm 3+ and Dy 3+ substitution, respectively. The magnetization increased with increasing difference in ionic radii of host Bi 3+ (1.17 Å) ion and dopant Ce 3+ (1.14 Å), Sm 3+ (1.08 Å) and Dy 3+ (1.03 Å) ions. UV–Visible diffuse reflectance spectra showed a sharp absorption in visible region and energy band gap values variation in the range 2.2 eV–2.33 eV.

La doped lead titanate ceramic compositions Pb 1− x La x TiO 3 (PLT) for x = 0.0, 0.05, 0.1, 0.2 and 0.3 were synthesized by an acrylic acid modified sol-gel route. The microstructure, surface morphology, and optical properties of the resulting compositions were studied by using TGA, X-ray diffraction, Raman Spectroscopy, and UV–Vis spectroscopy. It was found that the acrylic acid acts as a strong gelling agent and the organic residue gets removed completely below 450 °C. Very smooth ceramic powders characterized by single perovskite phase were obtained. A reduction in the tetragonality ratio from 1.0698 to 1.0033 was observed with increasing La content from x = 0.0 to x = 0.3. The effect of reduced tetragonality was corroborated by the peak shift of soft modes in Raman spectra and approximately 2 cm −1 downshift of E(TO 1 ) mode was observed for each atomic weight percent La addition in lead titanate. The average grain size was found decreasing marginally with the increasing La content in PLT. Using the UV–vis data, a slight but systematic increase in the direct absorption edge (band gap) from 3.155 eV to 3.234 eV was observed with increasing La content in the PLT compositions.

In this research work, we have proposed a one-dimensional (1D) defective annular photonic crystal (DAPC) ( AB ) 5 CDC ( AB ) 5 to identify the presence of reproductive progesterone and estradiol hormones in women. The periodicity of the proposed biosensing design made up of 1D annular photonic crystal (APC) has been broken by introducing a cylindrical cavity D of porous gallium nitride (GaN) material. The inner and outer faces of cylindrical cavity D are surrounded by concentric cylindrical buffer layers of magnesium fluoride (MgF 2 ) material. We have used a modified transfer matrix method with the help of MATLAB software to carry out investigations pertaining to the proposed theoretical work. The two distinct categories of blood samples containing reproductive hormones of different concentrations have been used in this work. The sensitivity of proposed 1D DAPC varies between 159.673 nm nmol −1  L −1 to 170.1525 nm nmol −1 L −1 when a cavity is infiltrated with a blood sample having progesterone hormone whose concentration varies between 0 and 200 nmol L −1 . Moreover, the sensitivity of the structure varies between 158.7816 nm nmol −1 L −1 to 170 nm nmol −1 L −1 under the influence of blood samples having estradiol hormones of different concentrations. In order to evaluate the performance of the proposed biosensor in the true sense we have also computed quality factor ( Q ) and figure of merit ( FoM ) values of the biosensor corresponding to both categories of blood samples of different concentrations. Our study shows that biosensors made up of 1D annular photonic structures are more efficient in comparison to the biosensors made up of planar 1D photonic crystals. Apart from detecting the reproductive hormones in females such kind of APC-based specialized biosensing devices may be very useful in the field of medical engineering and technology.

Here we reported structural, electrical, magnetic, and thermal transport properties of ternary pnictide bulk iron based compound EuFe 2 As 2 (Eu-122). This compound (Eu-122) crystallized in ThCr 2 Si 2 -type tetragonal phase structure with space group I4 / mmm at ambient temperature. A promising divalent state (Eu 2+ ) of Eu-ions was observed in the studied EuFe 2 As 2 . Magnetic ordering of Eu 2+ ions takes place at very low temperature at around T N = 20 K in EuFe 2 As 2 . The ferromagnetic interactions between Fe–Fe ions were established at higher temperature which was revealed from magnetic susceptibility measurements with negative value of the paramagnetic Curie temperature. Both magnetic phase transitions (20 K and 190 K) were clearly established the intrinsic magnetic nature revealed by both electrical transport and specific heat measurement. However the phase transition at low temperature corresponds to the magnetic ordering of Eu 2+ ions while the high transition temperature is due to the itinerant moment of Fe. EuFe 2 As 2 is the only compound among various parent compounds of iron pnictide superconductor’s family, in which both spin density wave (SDW) of Fe and A-type antiferromagnetic (AFM) ordering of the localized Eu 2+ magnetic moments take place simultaneously. We observed here that the localized character of Eu anti-ferromagnetism dominated via RKKY interactions, despite the largely itinerant nature of Fe magnetic interactions. The resistivity with applied magnetic field revealed that the AFM ordering temperature of Eu 2+ ions suppress with applied magnetic field. Also resistivity under hydrostatic pressure measurements shows the T SDW (Fe) transition of the Fe moments shifts towards the lower temperatures while AFM ordering of Eu 2+ decreases with pressure and the same is completely disappears at 2 GPa.

Using radio-frequency (rf) sputtering technique tungsten oxide (WO 3 ) thin films (∼150 nm) were deposited in a gas mixture of Ar and O 2 at 10 mTorr pressure on indium tin oxide (ITO) and corning glass substrates. The films were annealed at 400 °C. Structural and optical properties of films were studied. Metal–insulator–metal (MIM) structure was made by depositing metal electrode (Ag, Al, Au) on the prepared WO 3 thin films (on ITO substrate) using thermal evaporation technique. Electrical properties of the MIM structure were studied by plotting current versus voltage ( I – V ) curves for Ag, Al and Au metal electrodes. Current conduction mechanism in WO 3 film was determined by plotting and fitting I – V data in different equations of current mechanisms.

The Stoner–Wohlfarth (SW) model is a very lucid way of describing the dynamics of a single domain particle whose switching properties are important for storage applications such as magnetic random-access memory. This model explains the ideal case hysteresis and angular dependence of magnetization curves of aggregation of single domain particles with uniaxial anisotropy. Based on the energetics of a ferromagnetic particle and using atomistic simulations solving the Landau Lifshitz Gilbert equation, we study the hysteresis loop of a 1 nm ellipsoidal cobalt nanoparticle. The simulated M – H plot also displays the hysteresis branch crossing behavior when the field is applied close to the hard-axis.

In this paper we have used Monte Carlo simulations to study the two dimensional Coulomb glassmodel at half filling. The simulations were carried out using the Metropolis algorithm at zero and small finite disorder. We have used two protocols namely quenching and annealing to find the ground state of the system. In the quenching protocol at zero disorder, we looked at the effect of temperature on the efficiency of finding the ground state. The efficiency does not improve by decreasing the temperature. Since efficiency for quenching protocol was very low, we then used the annealing protocol to find the minimum energy state of the system. The annealing protocol was much more efficient than the quenching procedure. At finite disorder less than the critical disorder, the efficiency of the quenching protocol decreased compared to the zero disorder case. These results have been discussed in terms of domain theory and the density of states.

The modeling of experimental data for adsorption is a very important means of predicting the mechanism of various adsorption systems. The experimental data for variation of conductivity of pristine and SnO 2 functionalized single walled carbon nanotubes with concentration of nitrogen dioxide and ammonia gases (2 ppm–20 ppm) has been correlated with theoretical isotherm models. Studies are done with a one parameter model: Henry’s isotherm and two parameter models: Langmuir isotherm, Freundlich isotherm and Temkin models. Regression analysis is used to see the compatibility of theoretical models with the experimental data. The Freundlich isotherm shows the maximum compatibility with the experimental results with maximum value of regression coefficient and minimum value of average relative error suggesting the heterogenous nature of the surface. The calculated values of different constants for the four models indicate the increased adsorption capacity in case of functionalized single walled carbon nanotubes. This may be attributed to increase in heterogeneity and enhanced surface area.

In this paper, experimental studies on blend gel polymer electrolyte membranes comprising of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) saturated with 0.1 M liquid electrolyte of sodium tetrafluoroborate (NaBF 4 ) in the mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) are presented. Membranes are prepared by phase inversion technique. The effect of blending on the ionic conductivity, electrochemical stability window, ionic transference number, and cation transport number has been investigated using complex impedance spectroscopy, linear sweep voltammetry and DC polarization technique. Ion dynamics in the electrolyte membranes has also been investigated using dielectric studies. The optimized electrolyte membrane with composition PVDF:PMMA (95:5) + 0.1 M NaBF 4 + EC + DEC shows highest ionic conductivity of 0.6 mS cm −1 which follows Vogel–Tamman–Fulcher (VTF) behavior with temperature. The membrane shows an electrochemical stability window of 3.5 V and sodium ion transport number as ∼0.33.

All-solid-state polymer electrolytes have grown in significance for next-generation energy storage devices because of their high energy endurance, safety, and flexibility. Electrolytes made of poly(ethylene oxide) (PEO) have received a lot of interest because they can dissolve a wide range of ionic salts. We have observed the effects of lithium bis(trifluoromethanesulfonyl)imide salts on the structural, electronic, and thermal properties of solid-state polymer electrolyte systems incorporating PEO using methods based on density functional theory. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) i.e., HOMO-LUMO gap of the PEO and polymer electrolyte are found at 5.74 eV and 3.84 eV, respectively. The value of the HOMO-LUMO gap for PEO and solid-state polymer electrolyte shows similarity with the previous studies. The global and local chemical descriptors are calculated using the HOMO-LUMO gap. The electrochemical stability analysis is performed using the HOMO-LUMO method. Thermal functions also have been studied using density functional theory techniques. The theoretical vibrational frequencies of PEO and solid-state polymer electrolyte are investigated and compared with experimental values.

High loadings of coarse alumina trihydrate (ATH), commercially used in polymers as a fire-retardant filler, cause uneven dispersion and reduce workability and affect physicomechanical properties. Better tensile properties can be achieved by uniform dispersion of nanosize ATH in polymers while maintaining its flame-retardant properties. Consequently, mechanical milling, being a sustainable approach towards the creation of nano-size materials, was carried out to reduce the particle size of coarse ATH in a high-energy planetary ball mill. Investigations were carried out to optimize the milling parameters such as time, rotational speed, milling media size and feed size. During milling, some of the physical properties of ATH change. The energy profile was studied to get the desired product properties. Nano-ATH within the PP matrix reduces the loadings with improvement in tensile and flexural strength. Hence, lightweight PP/nano-ATH composites for suitable use can be developed.

The thermal properties of aluminium nitride nano-particles (n-AlN) filled into low-density polyethylene (LDPE) are discussed. Cylindrical specimens were prepared using a melt mixing process. X-ray diffraction was performed to characterize the structural properties of the pellets under investigation. The X-ray diffraction analysis confirms the change in secondary structure, such as crystallinity, of the LDPE due to the dispersion of n-AlN powder. The thermal stability of pure and n-AlN filled LDPE was checked by performing thermo-gravimetric analysis. The analysis confirms an improvement in the thermal stability of LDPE due to n-AlN addition. The thermal conductivity of the samples was measured using a KD 2 Pro device (based on the transient hot wire technique of thermal conductivity measurement) at room temperature. Our finding reveals ∼1.36 fold enhancement in the effective thermal conductivity of LDPE due to the addition of 15 vol.% of n-AlN. The room-temperature thermal conductivity data of the investigated pellets were analyzed as a function of n-AlN concentration in the light of available theoretical models and correlations. The variation in thermal conductivity data of LDPE with n-AlN concentration is well explained by the semi-empirical model proposed by Agari and Uno.

Thermophysical properties are calculated to determine performance parameters comprising specific heat capacity, thermal conductivity, thermal diffusivity and they are directly related to the dynamics of the material at atomic level and for thermal treatment of mustard husk (MSH) and MSH char, they play a vital role. Temperature dependence of thermophysical properties of MSH and MSH char have been investigated within the temperature range between 30 and 110 °C. MSH char is synthesized by the microwave pyrolysis of MSH. Thermogravimetric analysis of MSH and MSH char confirmed that MSH is more thermally stable as compared to MSH char. Moreover, it gave information about the degradation behaviour of MSH and MSH char. Thermophysical properties are measured by thermal analyser, based on the transient hot wire technique which is suitable to measure the thermal conductivity at elevated temperatures. At room temperature, thermal conductivity and thermal diffusivity of MSH are 0.187 W m −1  K −1 and 0.132 mm 2  s −1 , respectively. Specific heat capacity of MSH and MSH char are found to be almost same (1.349 kJ kg −1  K −1 for MSH and 1.310 kJ kg −1  K −1 for MSH char). Thermal conductivity and thermal diffusivity values are decreasing on increasing the temperature while specific heat capacity is increasing linearly on increasing the temperature. Low thermal conductivity and thermal diffusivity values of MSH imply that the conventional conductive heating is less effective and inefficient for the thermal treatment of MSH.

Anthropogenic dyes are one of the major pollutants often found in industrial wastewater. They are very stable as they contain robust aromatic moiety and are highly hazardous to human health and livelihood. There are several methods for the treatment of dye-containing wastewater. However, these techniques have severe limitations in terms of cost, the time required, and the generation of secondary waste. In this regard, silver nanoparticle-based catalysts can prove to be highly useful. In the present study, silver nanoparticles were synthesized by a green method, and the condition of synthesis was optimized by varying different parameters such as the concentration ratio of metal salt and plant extract, temperature, and pH of the reaction medium. The biogenic silver nanoparticles can act as a catalyst in the reductive degradation reaction of an anthropogenic dye (methylene blue) in the presence of sodium borohydride. The synthesized nanoparticles were highly active against methylene blue and degraded the dye within a few minutes. Thus, this work represents a very stable and efficient system for dye-containing wastewater treatment.

AlGaN/GaN heterostructures are one of the most promising semiconducting structures for fabricating high-speed and high-power electronic devices such as high electron mobility transistors and heterojunction bipolar transistors. Due to the lack of native substrates, these epitaxial structures are generally grown on foreign substrate materials such as sapphire, SiC and Si by using two-step growth techniques. In this paper, a few test structures along with TLM pads, FET structure, ohmic contacts and Schottky contacts have been fabricated on AlGaN/GaN heterostructure by photolithography, reactive ion etching, and e-beam metallization. Transmission line measurement has been used to calculate the sheet resistivity and contact resistance of ohmic pads. Current voltage measurement is used to test an FET structure of size 1 × 150 µm 2 with a gate length of 4 µm and source to drain spacing of 5 µm.

In this paper, we report the role of the interfacial polarization electrical field in thermal conductivity of In x Al 1− x N/GaN superlattice. Thermal conductivity reduction is one recent effort to improve thermoelectric device efficiency because a small reduction in thermal conductivity can enhance the figure of merit significantly. Quantum size effect and thermal boundary resistance are responsible for this reduction. The theoretical results demonstrate that the interfacial polarization electric field modifies acoustic phonon properties through elastic moduli and phonon group velocity as a result of the inverse piezoelectric effect. This enhances phonon scattering and thermal boundary resistance. Consequently, the thermal conductivity of the superlattice is reduced. Room temperature thermal conductivity is found to be 2.94 (3.35) W m −1  K −1 for In x Al 1− x N/GaN superlattice ( x = 0.17) in the presence (absence) of an electric field.

This work presents the sensitivity assessment of gallium nitride (GaN) material-based silicon-on-insulator fin field effect transistor by dielectric modulation in the nanocavity gap for label-free biosensing applications. The significant deflection is observed on the electrical characteristics such as drain current, transconductance, surface potential, energy band profile, electric field, sub-threshold slope, and threshold voltage in the presence of biomolecules owing to GaN material. Further, the device sensitivity is evaluated to identify the effectiveness of the proposed biosensor and its capability to detect the biomolecules with high precision or accuracy. The higher sensitivity is observed for Gelatin ( k = 12) in terms of on-current, threshold voltage, and switching ratio by 104.88%, 82.12%, and 119.73%, respectively. This work is performed using a powerful tool, three-dimensional (3D) Sentaurus Technology computer-aided design using a well-calibrated structure. The results pave the way for GaN-SOI-FinFET to be a viable candidate for label-free dielectric modulated biosensor applications.

This work presents the temperature-dependent analysis of heterojunction-free gallium nitride (GaN) FinFET through optimization of controlling gate parameters and dielectric materials. The temperature-dependent performance evaluation presents in terms of the transfer characteristic, transconductance, subthreshold swing (SS), and drain-induced barrier lowering (DIBL). Further, parametric assessment has been performed by gate length ( L g ) and oxide thickness ( t ox ) variation for optimization. Moreover, the different gate dielectric materials (Al 2 O 3 , ZrO 2, and Si 3 N 4 ) have also been used for different temperatures to optimize suitable gate dielectric material for improved performance of the device. Thus, GAN FinFET can be considered a promising component in high temperatures in IC and RF amplifiers.

Of late, the exploding wire technique (EWT) is being popularly utilized for high yield synthesis of diverse nanomaterials. In this paper, we propose an equivalent electrical circuit-based model of this technique when the explosion of wire against a metallic plate takes place in the presence of aqueous medium. The wire transforms into plasma state immediately after explosion and formation of liquid-vapour mixed phase is imminent in this process. We elucidate the conversion of metallic wire into partially ionized plasma by a set of semi-empirical mathematical equations. We propose a mathematical electrical conductivity model for analysing complex behaviour of wire explosion in a liquid medium. The present work results are restricted to one-dimension but could be extended to two- and three-dimensional codes associated with the dynamics of z -pinch or x -pinch.

Plasma technology has been an integral part of the semiconductor industries, especially to achieve the desired etch and selectivity of the outcome. These outcomes depend on various factors including the confinement of the charged particles of the plasma source. One of the widely employed confinement schemes is the multipole arrangement of magnetic fields, also known as a multicusp. Such arrangement provides minimum-B field value near the plasma axis and plays significant role in plasma-based ion sources for material processing and in plasma thrusters for spacecraft applications. In the present work, a novel rotating multicusp about its axis is studied to investigate its effect on the confinement of electrons present within it. The multicusp is allowed to rotate with a finite rotational speed, in the range of 0–10 7 rotation per second, thus inducing an axial electric field. It will lead to a directed axial flux of the electrons, determined by the rotational speed of the multicusp. The dynamics of the electrons enclosed within a rotating multicusp have been studied to explore its radial confinement. The results are of significance for semiconductor industries and others where downstream or afterglow plasmas are utilized for material applications.