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A two-dimensional analytical model is proposed in this paper for surface potential and drain current on Triple Material Surrounding Gate Junctionless Tunnel Field Effect Transistor (TFET). The purpose of this theoretical analysis is to break down two 1D equations of the 2D Poisson Equations. In this model, Triple Material Gates are decomposed into three different individual gates with different work functions. The Finite Differentiation Method is being enforced for this reason. By applying sufficient boundary constraints, the decomposed individual 1D Poisson equations are combined. In essence, this decreases the difficulty of solving Poisson equations in 2D. The analytical model proposed makes expressions of surface potential and drain current simpler. The reduction in the subthreshold swing which makes the device useful for low power applications. Finally, the outcomes of the study are correlated with the TCAD simulation. The proposed model is therefore validated to explain the nature of the Triple Material Surrounding Gate Junctionless TFETs.

In this paper, the analytical modeling of Trigate Junctionless FinFETs has been explored. The analytical model expresses the potential distribution, minimum center potential and threshold voltage. The variable separation method has been used to develop the potential distribution and threshold voltage. Further, the analytical model analyzed for different device parameters of Fin width, Fin height, Gate oxide thickness and gate work function. The analytical model results are compared with Synopsys TCAD results which proves the validation of proposed analytical model.

In nanoregime, heterojunction diodes have efficient applications in design and fabrication of sensors. Heterojunction diodes are formed by fusing two dissimilar semiconductors. Based on the combination of the materials used, these heterostructures find applications in bioelectronics and miniaturized sensors. In the literature, many different combinations are prevailing –GaN/AlGaN, Au/ZnO, NiO/ZnO. In this paper, a heterojunction diode is designed using Si/ ZnO combination and for the first time,the device is discovered to be used as pressure sensors.. The IV characteristics, energy band profile and CV curves of Si/ZnO is studied, analyzed and validated using TCAD-ATLAS software. This paper also proves that the performance of the device fits well for pressure sensing applications using COMSOL software.

The promising capability of Triple Material Surrounding Gate Junctionless Tunnel FET (TMSG – JL – TFET)based 6T SRAM structure is demonstrated by employing Germanium (Ge)and High-K gate dielectric material. The high – K insulation guarantees the proposed device to be used in low leakage memory systems. The corresponding analytical model is developed to extract various device parameters such as surface potential, electric field and threshold voltage. The results yield minimization of hot carrier effects at the drain end, when compared to conventional Silicon (Si) based tunnel FETs (TFETs). Further, the ambipolar characteristics of the proposed device is explored and 6T Ge – TMS – SG – JL – TFET based SRAM design is proposed. The results are compared with CMOS based SRAM and the analytical model presented is validated using 3D-TCAD ATLAS simulation, which ensures the accuracy and exactness of the developed model.

In this study, we present an ambipolar conduction and RF stability performance for a Germanium Source Dual Halo Dual Dielectric Triple Material Surrounding Gate Tunnel FET (Ge(SRC)-DH-DD-TM-SG-TFET). The energy band diagram of the device will be derived using the Stern Stability Factor. The minimum tunneling length is expressed using low-k Silicon dioxide (SiO2) and high-k Hafnium oxide (HfO2) as dual dielectric material. Then the band to band tunneling (BTBT) rate tunneling generation rate will be derived using Kane’s model. In terms of frequency efficiency the proposed device with SiO2/HfO2 as gate dielectric is good enough to attain high cut-off frequency (fT) of 94.22 GHz is observed at drain to source voltage of VDS = 1 V. Efforts have also been made to properly assess the potential of the two halo doped regions regions. An expression for transconductance is proposed and the model is validated using 3-D Silvaco Atlas TCAD device simulator. In addition, to demonstrate the advantage of using Ge(SRC)-DH-DD-TM-SG-TFET dual dielectric halo doping in circuit applications, the transient response of the conventional TFET germanium source is compared with the low and high-k dielectric halo doping Ge(SRC) TFET.

In this paper, a novel two-dimensional analytical model for threshold voltage on Dual Material Surrounding Gate Junctionless MOSFET is proposed. The analytical study is aimed at decomposing the 2-D Poisson Equations into two 1-D equations. This decomposition enables modeling of Dual Material Gates into two individual single gates. For this prospect, the Finite Differentiation Method is applied. The decomposed individual 1-D Poisson models are combined by employing relevant boundary constraints. This, in turn, provides a normal and easy solution for equation related to complex 2-D Poisson. The proposed potential model facilitates expressions of threshold voltage and sub-threshold swing. Finally, the simulation results and the analytical results were compared with the simulations obtained from TCAD which showed significant compatibility. Thus, it is defended that the proposed model illustrates the guidance regarding the designing of Dual Material Surrounding Gate Junctionless MOSFETs.

A simple physics-based three-dimensional (3-D) analytical model for AlInSb/AlSb/InSb double-gate high-electron-mobility transistors (DG-HEMTs) is presented. The model accurately predicts the short-channel effects (SCEs) in the channel region for various device dimensions, viz. channel length and width, by solving the three-dimensional Poisson equation. The effects of the barrier layer (AlInSb) thickness and the high doping concentration on the threshold voltage are also considered. Analytical expressions for the surface potential and threshold voltage are derived, and the analytical results closely match those obtained from Sentaurus technology computer-aided design (TCAD) simulations. The drain current and transconductance of the AlInSb/AlSb/InSb double-gate HEMT device are compared with experimental data obtained for a quantum-well field-effect transistor (QWFET). The proposed AlInSb/AlSb/InSb double-gate HEMT shows excellent properties for use in high-speed and low-power applications.

The Gaussian-doped junctionless FinFET (GD-JLFinFET) is investigated for radiofrequency (RF)/analog applications. The performance of the device is analyzed by computing the transconductance (gm), transconductance-to-drain current ratio (gm/Ids), cutoff frequency (fT), and maximum oscillation frequency (fmax). The stability factor (K) is analyzed based on the Y-parameters, and the linearity of the proposed device is studied based on the gm3, second-order voltage intercept point (VIP2), third-order voltage intercept point (VIP3), third-order intermodulation intercept point (IIP3), third-order intermodulation distortion (IMD3), and 1-dB compression point. The impact of device geometrical parameters such as the fin width, fin height, channel length, voltage biases, and temperature on the RF/stability characteristics is also studied. The proposed device exhibits fT = 2.96 THz and fmax = 9.13 THz, compared with the values of fT = 0.97 THz and fmax = 5.88 THz for the uniformly doped junctionless FinFET (UD-JLFinFET). It is observed that proposed device exhibits better RF/analog characteristics.

In this article, a two dimensional (2-D) threshold voltage modeling based gate and channel engineering are developed analytically for Dual Halo Gate Stacked Triple Material Dual Gate Tunnel FET (DH-GS-TM-DG-TFET) with effective surface charge. The model is derived by solving the 2-D Poisson equation in Silicon graded channel region using suitable boundary conditions. The proposed model incorporates the effects of various device parameters such as channel potential, electric field, DIBL, threshold voltage roll-off and drain current. Also, the fringing capacitance characteristics of the proposed DH-GS-TM-DG-TFET demonstrate superior performance over Triple material double gate and Single material double gate TFET structures. It is evident that the proposed device structure DH-GS-TM-DGTFET provides poor outflow current IOFF (10−16A/μm), and remarkable betterment in ON current (10−6A/μm). Moreover, the ION/IOFF ratio is 1010. To validate the robustness of model, the numerical results are compared with those obtained using Sentaurus TCAD.

This paper investigates the RF Stability performance of the Germanium Source Dual Halo Dual Dielectric Triple Material Surrounding Gate Tunnel FET Ge(SRC)-DH-DD-TM-SG-TFET using 3D - Silvaco Atlas TCAD device simulator. The impact of the geometrical parameter, high-k dielectric material and bias conditions on the key figure of merit (FoM) like Transconductance (gm), Gate capacitance (Cgg) and RF parameters like Stern Stability Factor (K), Critical Frequency (fk) are investigated. The analytical model provides the relation between fk and small signal parameters which provide guidelines for optimizing the device geometrical parameter. The results show improvement in ION current, gm, ft and fk for the optimized device structure. The optimized Ge(SRC)-DH-DD-TM-SG-TFET exhibits fk of 75.0 GHz.

This paper proposes a 2-D analytical model developed for Double Gate Junctionless Transistor with a SiO2/HfO2 stacked oxide structure. The model is solved by Poisson’s equation using the variable separation method. The proposed model gives analytical expressions for electrostatic potential distribution, threshold voltage and drain current with the effects of depletion regions at source/drain side. Furthermore, the potential and drain current models are used to evaluate the Short Channel Effects (SCEs) of the proposed device. The electrical characteristics and SCEs are analyzed by different possible definitions of channel length, silicon thickness, equivalent oxide thickness, and depletion length variations. The developed model results are validated through comparison with Sentarus TCAD simulator results. In addition, the proposed device is also studied for the digital circuit performance of CMOS inverter circuit by the voltage transfer characteristics, transient analysis, and AC small signal analysis.

An improved subthreshold analytical model of Germanium source Dual Halo Dual Dielectric Triple Material Surrounding Gate Tunnel FET Ge(SRC)-DH-DD-TM-SG-TFET is proposed. The dielectric gate oxide structure is comprised of Silicon-dioxide and Hafnium oxide. The high-K dielectric materials overcomes the Short Channel Effects caused by ultrathin silicon devices. The subthreshold analysis is carried out by solving a 2-D Poisson’s equation using the parabolic approximation method. The electrical characteristics of Ge(SRC)-DH-DD-TM-SG-Tunnel FET are analyzed using a 3-D Sentaurus TCAD device simulator and compared with the silicon based single halo and triple material surrounding gate TFET structures. The proposed model shows a lower ambipolar current and a better ION/IOFF ratio of 106. Moreover, the influence of germanium/silicon in dual dielectric materials has reduced the tunneling barrier width and the ON current (10−4 A/μm) of the proposed device and improved at the level of CMOS transistors.

An accurate two dimensional subthreshold modeling of Germanium based Dual Halo Gate stacked Triple Material Surrounding Gate (Ge-DH-GS-TM-SG) tunnel field effect transistor is proposed for the first time in this paper. The model is solved by Poisson's equation using parabolic approximation method. The developed model gives analytical expressions for surface potential, electric field, threshold voltage, drain current, trans conductance to drain current ratio, subthreshold current and subthreshold swing are used to evaluate the short channel effects. The subthreshold swing of the proposed Ge-DH-GS-TM-SG-TFET is compared with Silicon based Single Halo Triple Material Surrounding gate TFET(Si-SH-TM-SG-TFET)and Triple Material Surrounding Gate TFET(TM-SG TFET). It is noticable that the proposed device Ge-DH-GS-TM-SG-TFET structure provides. poor outflow current IOFF (10−15A/μm), and remarkable improvement in ON current. (10−5A/μm).Moreover, the ION/IOFF ratio is 108. The developed model results are validated through comparison with 3-D sentaurus TCAD simulator results.

The prototype of Fe doped Dual Material Gate AlGaN/AlN/GaN High Electron Mobility Transistors(HEMTs) developed by a Finite Difference Method(FDM) is addressed in this paper. The equations are illustrated in a way that the dual material gate disintegrates into two distinct single material gates by discreting one 2-D equation into two isolated equations. The boundary conditions conclude in the clubbed model of two 1D equations. The work functions of two metal gates, their length difference and applied drain voltage, the proposed model estimates the Channel potential, Electric field, Threshold voltage and Drain current. A momentous increase of the drain current is witnessed when the δ-doping is integrated in the AlN layer. These features are also validated by TCAD simulations.

In this paper, an analytical model for modified Surrounding Gate Tunnel FET with gate stack engineering and different gate metals has been developed. Further, considering the scaling advantageous of Gate stack engineering and high degree performance of dual material engineering, the both has been integrated into a novel structure known as Surrounding Gate (SG) Tunnel FET with stacked oxide SiO2/high-k and dual material (DM) has been proposed. The two dimensional (2D) potential at the surface and electric field mathematical models for the DMSG TFET are developed by solving 2D Poisson's equation with matching device boundary conditions. Based on the Kane's formula, mathematical expression for the band-to-band (BTB) tunneling generation rate is derived and then used to calculate the drain current. The impact on the proposed device performance due to the variation of different device parameters has also been studied. It has been found from the presented results that the ON current of the DMSG TFET with stack is 10-6A, OFF current is 10-13A and ON/OFF ratio is 107. The mathematical results have been verified using the simulated results obtained from TCAD, a 3-D device simulator from ATLAS.

A subthreshold analytical model for Dual Material Double Gate Junctionless Tunnel FET (DMDG JLTFET) is developed. To analyze the behavior of short channel device, relevant parameters such as surface potential, electric field, threshold voltage, drain current, transconductance-to-drain current ratio, subthreshold slope and subthreshold swing are extracted from the 2-D analytical solution of Poisson's equation. Relating DMDG JLTFET to Junctionless MOSFETs, the results show significant reduction of Short Channel Effects (SCEs) at the drain end. The analytical model for DMDG JLTFET is effective due to the combined supremacy of uniform doping in the channel, usage of high-K gate dielectric material and work function engineering in the gate metal. The results obtained from the analytical model are simulated and validated using 2-D Sentaurus TCAD device simulator.

In the recent times, the performance of MOSFET in the nanoscaled region attains improvisations through several alternative device structures. Amongst many advanced MOSFET structures, the Double Gate (DG) MOSFET is one such structure which mitigates short channel effects because of its excellent scalability. Among the various structures, FET- based biosensors have shown an accelerated growth recently. Even though many analytical models are available for the Dual Material DG (DMDG) MOSFET structures, this work endeavours to introduce an analytical modeling of nanocavity embedded DMDG structure for the first time. The expression for surface potential is obtained by solving the 2-D Poisson’s equation using a parabolic-potential approach. The threshold voltage is determined from the minimum surface potential model. Sensitivity is computed in terms of relative change in the threshold voltage and it is derived using the model. The influence of various device geometrical parameters like length and thickness of the nanocavity on the sensitivity has been investigated. Further, a comparison of the sensitivity of DG MOSFET and DMDG MOSFET has also been made and the derived results are validated against TCAD simulation results.

This paper presents an approximate solution of a 2D Poisson’s equation within the channel region for Double-Gate AlInSb/InSb High Electron Mobility Transistors (DGHEMTs), using variable separation technique. The proposed model is used to obtain the surface potential, electric field, threshold voltage and drain current of both tied and separated gate bias conditions for Double-Gate AlInSb/InSb HEMTs. The surface potential and electric field are derived for both effective conduction paths of front and back heterointerface by a simple analytical expression and an analytical solution is verified with sentarus TCAD device simulator.

The impact of temperature in carrier transport of scattered SiNW MOSFET has been developed. Scattered SiNW MOSFET model includes the effects of elastic scattering, optical phonon emission, surface roughness scattering and random discrete dopants. The temperature effect of above mentioned scatterings in the device limits electron mobility, decreasing device current and transconductance. This work discusses the detailed behavior of analog parameters like transconductance (gm) and early voltage (VA). The validity of the proposed model has been confirmed by comparing the analytical results with the technology computer aided design simulation results.

The magnetization of noninteracting metallic nanoparticles is investigated by comparing the particle-size and temperature dependences of the magnetization for several mechanisms. The nanoparticle magnetization deviates from that of the underlying bulk materials due to zero-temperature and thermal effects, and on a mean-field level, the corresponding surface-core interaction is described by a Landau–Ginzburg approach. A major factor is the reduced atomic coordination at the surface, which has often, but not always, opposite effects on the zero-temperature magnetization and Curie temperatures. The coordination effect is particularly pronounced for very weak itinerant ferromagnets and for strongly exchange-enhanced Pauli paramagnets. With regard to external magnetic fields, the nanoparticle magnetization involves several “superparamagnetic” phenomena, namely, Neel relaxation, Brownian relaxation, and Langevin macrospin paramagnetism.

In this chapter, an analytical model for single gate AlInSb/InSb HEMT device has been developed. A 2D sub threshold analysis of the proposed device is done to evaluate the channel potential, electric field, sub threshold drain current which exhibits superior performance with AlInSb/InSb in terms of short channel effects and electron mobility in the channel. In addition to the above advantages, the AlInSb/InSb material is extensively used in high gain and low noise applications. Expression for channel potential, electric field, threshold voltage, drain current have been obtained. From the simulative study, we observe that the step function in channel potential suppresses the SCEs. The study of AlInSb/InSb HEMTparameters of the device by considering the variation of the first subband ,the second subband and sheet carrier charge density( with applied gate voltage() and the performance of the device was compared for various temperatures. The scaling theory for single gate AlInSb/InSb HEMT is derived with Effective conducting path effect. The potential in the effective conducting path and a simple scaling equation has been developed and on solving this equation the minimum channel potential Фdeff, min and the new scaling factor αis obtained to model the subthreshold behavior of high electron mobility transistors

We report the formation of complex core–shell and three-layer Mn–Bi nanoparticles in a single step inert-gas condensation process. These structures have been achieved by controlling the thermal environment of the nanoparticles. High resolution transmission electron microscopy, high-angle annular dark-field imaging in scanning transmission electron microscopy mode, and elemental mapping by energy dispersive spectroscopy have been used to determine the crystal structure and chemical composition of the nanoparticles. These particles exist in two forms: (1) a crystalline Bi core with an amorphous Mn-rich shell, and (2) a crystalline Bi annular shell between two amorphous layers with high Mn concentration. These particles show significant magnetic hysteresis possibly arising from the change in bond length between Mn atoms introduced by Bi atoms in the bonding environment of the Mn atoms.

In this paper, 3-D device simulations are performed to analyze the variations of uniform and non-uniformly (Gaussian) doped junctionless FinFETs. The impact of Fin width (Fw), Fin height (Fh), Channel length (Lg) and Gate Oxide (tox) on drain current, ION/IOFF ratio, subthreshold swing, Drain Induced Barrier Lowering (DIBL) of Si based Bulk Junctionless FinFETs is investigated. The results shows that the ION = 183μA/μm, IOFF = 4.449 × 10−5 μA/μm, is achieved for non-uniformly doping when compared to uniform doping configurations with ION = 102 μA/μm, IOFF = 3.05 × 10−5 μA/μm of junctionless FinFETs. Furthermore, the results also shows that non-uniformly doped junctionless FinFETs with fin width of 6 nm exhibits better DIBL of 22.5 mV/V and Subthreshold swing of 62.04 mV/decade than the uniform doped junctionless FinFET with DIBL of 80 mv/V and Subthreshold swing of 67.62 mV/decade. Thus, the non-uniformly doped junctionless FinFETs can effectively improve the performance of Junctionless FinFETs. In addition, to reduce the leakage current in bulk FinFETs effect of Punch-through Stop (PTS) layer, bulk doping concentration and body bias variations are studied. Finally, the 6T-SRAM circuit was implemented for JL-FinFETs and the results suggest that Gaussian doping JL-FinFETs strengthens the applicability of SRAM in the memory design.

A different analytical model for HEMT using InP comprising the effects of depletion across the region for In AIAs, while considering the short channel effect in InAlAs /InGaAs heterostructure. The sheet carrier density is obtained. In addition to this, depletion interference potential, through depletion width variation the effect of parallel conduction and $\Delta \mathrm{E}_{-}(\mathrm{c}-)$ E_fwith gate voltage is also obtained. The obtained results using MESFET analysis gives a different method for High Electron Mobility Transistor (HEMT).

An organic crystal of L-Alaninium oxalate single crystal, belongs to the amino acid group, was grown by the slow evaporation solution growth technique at room temperature. The grown crystal had been subjected to single-crystal X-ray diffraction technique and cell parameters of the crystal were determined. The quantitative analysis on the crystal had been carried out using Fourier transform infrared (FTIR) and Fourier transform Raman (FTRaman) spectral measurements. The molecular structures, vibrational wave numbers were calculated using Density Functional Theory method. The calculated Thermodynamic properties were performed.

The phase formation and magnetic behavior of SmCo 4 − x Fe x B ( x = 0, 0.25, 0.5, 0.75, 1 and 2) produced by melt spinning have been investigated. At x = 0, melt spinning resulted in the formation of the SmCo 4 B phase and an ultrahigh coercivity of 44 kOe at 300 K. Fe substitution resulted in the formation of an amorphous structure along with the Sm(Co,Fe) 4 B phase during melt spinning. A single Sm(Co,Fe) 4 B phase was observed after crystallization when x 4 B and Sm 2 (Co,Fe) 17 B y were observed when x ⩾ 1. Hysteresis loops at x x ⩾ 1. In the crystallized Fe-containing materials, an increase in both coercivity and magnetization with increasing Fe content was observed until x = 1. Initial magnetization curves revealed nucleation-controlled behavior at x x = 1 and x = 2. The average grain size for the annealed SmCo 4 − x Fe x B samples measured from TEM micrographs was 110 nm for both x = 0.5 and x = 1 and 90 nm for x = 2.

In this communication, the influence of solvent (water and mixed solvent) on the structural, surface microstructural, dc-electrical and optical properties of spray deposited cadmium oxide (CdO) thin films doped with different weight percentages (wt%) of boron (B) on microscopic glass substrates at 300 °C is reported. The X-ray diffraction (XRD) analysis suggests that the samples are polycrystalline in nature and the crystallinity is enhanced by B doping concentrations. The average crystallite size of (200) plane is ranging 29–90 and 40–138 nm for water, and mixed solvent of water and methanol (1:1), respectively. Oxidation state of B doped CdO thin film was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The surface microstructures of B doped CdO thin films are effectively modified by solvent and the average particle size varies between 301 and 466 nm for water solvent and 221 and 705 nm for mixed solvent used B doped CdO films. The direct optical band gap energy values varies between 2.11 and 2.35 eV for water and 2.43 and 2.54 eV for mixed solvent used B doped CdO thin films. High average transmittance (80 %) and high mobility of 64.42 cm2/V·s were obtained for 1.0 wt% B doped CdO thin film deposited using mixed solvent. The mixed solvent used 1.0 wt% B doped CdO thin film has high figure of merit (16.2 × 10−3 Ω−1). The variations in electrical resistivity, carrier concentration, mobility and optical transmittance with respect to spray solvents have been discussed.

In this paper, we propose new physically based threshold voltage models for short channel Surrounding Gate Silicon Nanowire Transistor with two different geometries. The model explores the impact of various device parameters like silicon film thickness, film height, film width, gate oxide thickness, and drain bias on the threshold voltage behavior of a cylindrical surrounding gate and rectangular surrounding gate nanowire MOSFET. Threshold voltage roll-off and DIBL characteristics of these devices are also studied. Proposed models are clearly validated by comparing the simulations with the TCAD simulation for a wide range of device geometries.

– In this paper, we have investigated the Scattering effects in Carrier Transport of Near-ballistic SiNW MOSFET, which incorporates elastic scattering, optical phonon emission and its combination with Roughness Scattering. Current–voltage (I–V) characteristics of Proposed model is compared with Natori’s Ballistic and Quasi-Ballistic Transport model. We study the impact of Surface Roughness in the device leads on the current variability of a Gate-All-Around (GAA) SiNW MOSFET, which shows a remarkable decrease in electric current, mobility variation and transconductance because of scattered mobility. Analog parameters like the transconductance (gm), the transconductance generation factor (gm/Id), the early voltage (VA) have also been investigated. Effectiveness of the proposed model has been confirmed by comparing the analytical results with the TCAD simulation results.

In this paper, analytical model for threshold voltage is derived for fully depleted Triple material Surrounding gate (TMSG) SOI MOSFET. Three gate material of different work functions are introduced in the SOI MOSFET structure to reduce the short channel effects. The two dimensional Poisson equation is solved and based on parabolic approximation method, the model for threshold voltage is developed. The threshold voltage is analyzed for device parameters such as gate length ratios, oxide thickness, silicon thickness, doping concentration. The results of the analytical model values are validated using MEDICI simulation.

Nanocrystalline titanium oxide (TiO 2 ) thin films were deposited on silicon (1 0 0) and quartz substrates at various oxygen partial pressures (1 × 10 −5 to 3.5 × 10 −1 mbar) with a substrate temperature of 973 K by pulsed laser deposition. The microstructural and optical properties were characterized using Grazing incidence X-ray diffraction, atomic force microscopy, UV–visible spectroscopy and photoluminescence. The X-ray diffraction studies indicated the formation of mixed phases (anatase and rutile) at higher oxygen partial pressures (3.5 × 10 −2 to 3.5 × 10 −1 mbar) and strong rutile phase at lower oxygen partial pressures (1 × 10 −5 to 3.5 × 10 −3 mbar). The atomic force microscopy studies showed the dense and uniform distribution of nanocrystallites. The root mean square surface roughness of the films increased with increasing oxygen partial pressures. The UV–visible studies showed that the bandgap of the films increased from 3.20 eV to 3.60 eV with the increase of oxygen partial pressures. The refractive index was found to decrease from 2.73 to 2.06 (at 550 nm) as the oxygen partial pressure increased from 1.5 × 10 −4 mbar to 3.5 × 10 −1 mbar. The photoluminescence peaks were fitted to Gaussian function and the bandgap was found to be in the range ∼3.28–3.40 eV for anatase and 2.98–3.13 eV for rutile phases with increasing oxygen partial pressure from 1 × 10 −5 to 3.5 × 10 −1 mbar.

There are two main thrusts towards new permanent-magnet materials: improving extrinsic properties by nanostructuring and intrinsic properties by atomic structuring. Theory-both numerical and analytical-plays an important role in this ambitious research. Our analysis of aligned hard-soft nanostructures shows that soft-in-hard geometries are better than hard-in-soft geometries and that embedded soft spheres are better than sandwiched soft layers. Concerning the choice of the hard phase, both a high magnetization and a high anisotropy are necessary. As an example of first-principle research, we consider interatomic Mn exchange in MnAl and find strongly ferromagnetic intralayer exchange, in spite of the small Mn-Mn distances.

The present work explores the impact of scattering in carrier transport of near-ballistic SiNW MOSFET. For the first time, a scattered SiNW MOSFET model is revealed which includes the effects of optical phonon emission, elastic scattering, surface roughness scattering and random discrete dopants. Impact of above mentioned combined scatterings in the device limits electron mobility which makes a remarkable decrease in device current and transconductance compared with our previous model and Natori's Ballistic transport model. This work discusses the detailed behavior of analog parameters like Transconductance (g(m)), Transconductance generation factor (g(m)/I(d)) and Early Voltage (VA). The proposed model has been validated by comparing the analytical results with the TCAD simulation results and it shows the good agreement.

The utilization of dual power control in a directional solidification system (DSS) is shown to help grow higher quality multi-crystalline ingots, particularly high performance ingots with seeded growth. Since the power ratio to the top and the side heaters is tunable, this allows optimal control of the power profile and the solidification front throughout the entire casting process. A dual power controlled DSS (DP-DSS) with separate power control to top and side has achieved faster melting, better seed retention, and more vertical grains while consuming less energy than a single power controlled DSS (SP-DSS).

Magnetic nanoparticles smaller than similar to 15 nm in diameter and with high magnetocrystalline anisotropies K-1 >= 1 MJ m(-3) can be used as building blocks for next-generation permanent magnets. Advances in processing steps are discussed, such as self-assembly, alignment of the easy axes and appropriate nanostructuring that will enable the fabrication of densely packed nanopartide assemblies with improved permanent-magnet properties. This study also proposes an idealized nanocomposite structure for nanoparticle-based future permanent magnets with enhanced energy products. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Organic scintillation materials are very much useful in the area of nuclear experiments, medical diagnostics and therapy. In the present investigation, we have systematically analyzed the vertical Bridgman grown organic scintillation material of trans-stilbene which is annealed at different annealing temperatures. Remarkable changes have been observed on its structural and optical properties. High resolution X-ray diffraction (HRXRD) analysis shows noticeable difference for the annealed specimen than the as-grown crystal. The observed results exposed that the crystalline quality was drastically improved by the elimination of defects or low angle boundaries by post growth annealing technique. Its optical behavior has been examined by photoluminescence, Raman and IR analyses. Vickers microhardness measurement has been carried out and found that hardness values increases for the annealed trans-stilbene single crystals.

The formation of magnetic moments in TiO clusters is investigated by hydroxylation experiments and model calculations. The clusters were produced by inert-gas condensation and in-situ oxidation and have an average size of 15 nm. Exposure to drastically alters the magnetism of titanium-oxide (TiO) clusters, especially for rock-salt TiO. The hydroxyl ions, created by moist-air treatment of Ti-oxide nanoparticles, enhance the magnetic moment of undoped TiO clusters by a factor of order 10, to about 13.5 emu/cm . A similar but much slower enhancement was observed in ambient air, whereas oxygen annealing reduced the moment. The phenomenon is explained by the creation and adsorption of hydroxyl groups at the particles' surfaces, a process closely related to the catalytic activity of TiO surfaces and to the creation of overlapping defect states in the band gap. Our theoretical analysis suggests that the hydroxyl groups effectively enhance the hopping integral and reduce the onsite energy on neighboring Ti atoms. Depending on the density of the hydroxyl defects, the defect states overlap and order magnetically, although not necessarily by a Stoner mechanism.

A uniaxial sulphamic acid single crystal having dimensions of 35 mm diameter and 150 mm length was grown. Employing slow evaporation technique sulphamic acid crystals of size 10×10×5 mm 3 were grown. Etching, microhardness, high-resolution X-ray diffraction, laser damage threshold, UV–visible, Thermogravimetric and differential thermal analysis were made on conventional and the Sankaranarayanan–Ramasamy method grown sulphamic acid crystals. Etching behaviour of the (1 0 0) plane of conventional and the Sankaranarayanan–Ramasamy method grown sulphamic acid crystals was investigated with different etchants. Vicker's microhardness test on the (1 0 0) plane confirmed the mechanical stability of the conventional and the Sankaranarayanan–Ramasamy method grown sulphamic acid crystals. High-resolution X-ray diffraction results show that the crystalline perfection of sulphamic acid single crystals grown by the Sankaranarayanan–Ramasamy method is extremely good compared to the conventional slow evaporation method grown sulphamic acid crystal. Thermogravimetric and differential thermal analysis was carried out to determine the thermal properties of the grown crystal.

The growth and characterization of a new metal-organic crystal [CS (NH2)2]2 · CoCl2 is reported. The growth of single crystal of BTCoC was accomplished from solution by slow evaporation method. The grown crystals were characterized by powder and single crystal X-ray diffraction, FT-IR, UV–Vis. and TG/DTA. The crystal structure and the unit cell parameters were analyzed from the X-ray diffraction studies. BTCoC crystallizes in the tetragonal system with the space group P42/n. The FT-IR spectrum analysis has confirmed the functional group in the BTCoC. The thermal behaviour of the crystals has been investigated by TG/DTA analyses. BTCoC has good optical transmission in the entire visible region, which is an essential requirement for a nonlinear crystal.

The recently discovered crystal growth method called uniaxially solution-crystallization method of Sankaranarayanan–Ramasamy (SR) is modified in some aspects and used for growth of triglycine sulphate (TGS) crystals. The modification leads to the simplicity, reduction of cost and avoided the temperature fluctuations. The 〈010〉 direction of TGS is very important and used for fabrication of infrared detectors. Using this method, the 〈001〉, 〈010〉 directional crystals of TGS were successfully grown in a glass crystallizer. The grown crystal was characterized by HRXRD, UV-Visible and dielectric studies. The results prove the suitability of the modified SR method for oriented TGS crystal. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this paper, we have formulated a two-dimensional (2D) analytical model for surface potential and electric field of a p-type tri-material gate (TMG) gate-all-around (GAA) nanowire tunneling field effect transistor (TFET). The proposed model includes the effect of voltage at the drain end, work functions of the gate metal, oxide thickness, and radius of the silicon nanowire. Incorporating the advantages of surrounding gate with three different gate material work functions, this nanostructure of TMG GAA TFET is proposed and shows improved electrical characteristics. Also a step change of potential along the channel is obtained, which screens the region R1 from the drain potential variations, thus reducing the drain control over the channel. This results in appreciable diminishing of short channel effects and hot carrier effects, which are investigated by developing a 2D analytical model. The analytical results are compared and verified with the simulation results.

In the field of nonlinear optics (NLO), the organic materials are relatively new comers compared to inorganic materials. Benzimidazole is an organic material presenting high nonlinear optical behaviour especially for second harmonic generation. Single crystals of benzimidazole are grown from vertical bridgman technique (VBT) by optimizing the growth conditions. The grown single crystals have been subjected to various characterization studies such as thermal, optical and mechanical properties. The obtained results and summary are given.

In the present study, x-ray diffraction, Raman spectroscopy, spectroscopic ellipsometry, photoluminescence, and x-ray photoelectron spectroscopy techniques were used to study the effect of 120 MeV 107Ag9+ ion irradiation on nanocrystalline Cu2O thin films grown by the activated reactive evaporation technique. The influence of dense electronic excitations during ion irradiation on the structural and optical properties of the Cu2O thin films was studied. Experimental results demonstrate that the phase and the size of nanocrystallites in the Cu2O thin films as well as associated surface states can be tailored by controlling ion fluence. The Cu2O higher symmetry cubic phase is observed to be quite stable under a higher temperature and irradiation-induced thermal spikes, which accompanies ion irradiation.

The present study reviews various synthesis techniques for preparing single-phase Cu2O nanoparticles. The ‘nanoparticle route’ results in the growth stable semiconductor materials via the size-induced stabilization at nanodimension. In comparison to other techniques, activated reactive evaporation (ARE) method has an excellent parametric control to obtain the nanoparticles in a wide size range. The size-dependent optical, structural and electronic properties of Cu2O nanoparticles prepared by ARE method have been discussed in detail. Increase in ionic nature of the Cu2O lattice and a surface-modified thin CuO shell surrounded Cu2O core stabilizes the Cu2O phase. High-energy heavy ion irradiation has been used to modify the nanocrystalline characteristics of the Cu2O nanophase without destroying nanoparticle nature. These results show that Cu2O nanoparticles based Schottky and heterojunction will be stable to yield better photovoltaic performance.

The structural and magnetic properties of nanostructured Co-rich transition-metal alloys, Co(100-x)TMx (TM = Hf, Zr and 10 ≤ x ≤ 18), were investigated. The alloys were prepared under non-equilibrium conditions using cluster-deposition and/or melt-spinning methods. The high-anisotropy HfCo7 and Zr2Co11 structures were formed for a rather broad composition region as compared to the equilibrium bulk phase diagrams, and exhibit high Curie temperatures of above 750 K. The composition, crystal structure, particle size, and easy-axis distribution were precisely controlled to achieve a substantial coercivity and magnetization in the nanostructured alloys. This translates into high energy products in the range of about 4.3-12.6 MGOe, which are comparable to those of alnico.

The effect of particle size distribution of CdS nanoparticles on the band-edge photoluminescence (PL) spectrum is investigated. The resulting inhomogeneously broadened lineshape is found to be asymmetric and depend on the width of particle size distribution. The calculated lineshape is fitted to the measured PL spectrum of 3.6 nm diameter CdS nanoparticles, which showed the band-edge PL peak around 3.00 eV and that due to recombination at defects at 2.56 eV. The parameters of the PL spectrum of a bulk CdS film are used as inputs for the fitting. The average particle size and the standard deviation of the size distribution are obtained from the analysis. The particle size estimated from the PL data is compared with that obtained from x-ray diffraction measurements.

In the present studies, CdxZn(1−xx)S nanoparticles have been prepared by chemical capping method. Optical absorption, X-ray diffraction and transmission electron microscopy studies have been carried out. Size of the nano particles have been calculated from the XRD and optical absorption data. These studies indicate towards a kinetically controlled growth of nano particles. The growth of the CdxZn(1−xx)S nano particles is also affected by the action of the capping agent.