Effect Of Mole Fraction Research Articles

Mole fraction effects on AlxGa1−xN/AlN/GaN MOSHEMT analog/RF performance: analytical model and simulation assessment

Mole fraction effects on AlxGa1−xN/AlN/GaN MOSHEMT analog/RF performance: analytical model and simulation assessment

The effect of mole fraction on the phase transition of BaxSr1-xTiO3 ceramic from cubic to tetragonal assisted by Rietveld analysis

The displacive phase transition in BaxSr1-xTiO3 (BST) ceramic due to the mole fraction differences was investigated using x-ray diffraction assisted by Rietveld analysis. Detailed Rietveld analysis showed that BST undergoes a structural phase transformation from cubic to tetragonal phase. Average crystallite size and microstrain present in the powders were studied using the Wilson and Debye–Scherrer equation. The crystal structure of samples was refined by the Rietveld method, and an expansion on the unit cell parameters was determined. These analyses revealed an increment in the unit cell strain and an increase in the crystallite size when the mole fraction was increased.

Temperature-dependence of impact toughness of bulk metallic glass composites containing phase transformable β-Ti crystals

A parametric study of the Charpy impact toughness of bulk metallic glass composites (BMGCs) containing crystalline β-Ti dendrites is conducted at different temperatures. The effect of mole fractions, size and phase transformability of the dendrites in the BMGCs on impact toughness, aK, is studied. BMGCs with non-transformable dendrites exhibit a steep drop in aK with decreasing temperatures whereas those with transformable dendrites resist embrittlement. This is attributed to the energy absorbed during deformation-induced martensitic transformation (DIMT) in the dendrites of the phase transformable BMGC. At a specific temperature, increasing the mole fraction of phase transformable β-Ti crystals up to 70% also improves aK, although further increase in mole fraction to 100% leads to embrittlement. The non-monotonic variation of aK is attributed to the relative differences in confinement of the dendrite by the matrix, which directly influences the occurrence of DIMT in the former. These BMGCs are also resistant to relaxation induced embrittlement as aK is insensitive to the casting size. The implications of these results in terms of designing BMGCs with high impact toughness for applications at low temperatures are discussed.

Effect of Mole fraction and Fin Material on Performance Parameter of 14 nm Heterojunction Si1-xGex FinFET and Application as an Inverter

Effect of Mole fraction and Fin Material on Performance Parameter of 14 nm Heterojunction Si1-xGex FinFET and Application as an Inverter

Modeling of electronic structure for dome-shaped quantum dots

A Hamiltonian operator in assessing the energy levels and wavefunctions of quantum dots (QDs) was proposed. The finite element method was used to solve the numerical Schrödinger equation for envelope function in the effective mass approximation. Within this model, we have investigated QDs with different geometries (cone, lens and dome-shaped dot). While it is easy to attain stability for conical QDs, it is difficult with lens QDs. Strain and mole-fraction effects are also studied. Our results coincide with the experimental one.

Effect of Ge Mole Fraction on Performance of Underlapped Gate-All-Around SiGe-Source Tunneling Field-Effect Transistors.

In this paper, we propose the design optimization of underlapped Si1-xGex-source tunneling field-effect transistors (TFETs) with a gate-all-around structure. The band-to-band tunneling rates, tunneling barrier widths, I-V transfer characteristics, threshold voltages, on/off current ratios, and subthreshold swings (SSs) were analyzed by varying the Ge mole fraction of the Si1-xGex source using a commercial device simulator. In particular, a Si0.2Ge0.8-source TFET among our proposed TFETs exhibits an on/off current ratio of approximately 1013, and SS of 27.4 mV/dec.

Modeling of electronic structure for dome-shaped quantum dots

A Hamiltonian operator in assessing the energy levels and wavefunctions of quantum dots (QDs) was proposed. The finite element method was used to solve the numerical Schrödinger equation for envelope function in the effective mass approximation. Within this model, we have investigated QDs with different geometries (cone, lens and dome-shaped dot). While it is easy to attain stability for conical QDs, it is difficult with lens QDs. Strain and mole-fraction effects are also studied. Our results coincide with the experimental one.

Synthesis and Performance Evaluation of BaxSr1 – xTiO3 Ceramic-Based MIM Capacitor for Energy Storage Application

Metal-insulator-metal (MIM) capacitor with high-k insulator such as BST enhances specific capacitance. The effects of barium mole fraction (x) of BaxSr1 – xTiO3 ceramic-based MIM capacitor on specific capacitance and leakage current density are reported in this article. BaxSr1 – xTiO3 nanopowder for various x are synthesized using solid-state reaction method and the performance parameters of Ag/BaxSr1 – xTiO3/Ag MIM capacitors are evaluated. The mean crystallite sizes are in 20 to 60 nm range. Ba0.7Sr0.3 TiO3 ceramics show higher relative permittivity owing to its higher mean crystallite size. The insulator with higher crystallite size at dominant orientation shows enhanced leakage performance. Ba0.1 Sr0.9 TiO3 ceramic capacitor shows optimum performance altogether.

Effects of mole fraction and surface wettability on evaporation of Ar/Kr mixtures: A molecular dynamics study

The phase transition of fluid on the solid surface plays an important role in engineering, while the mechanism of phase transition is still need to be studied in depth. Therefore, molecular dynamics simulations were employed to investigate the evaporation of different mole fraction of Ar/Kr mixtures on several wettability Pt substrates (weak hydrophobic surface, hydrophilic and weak hydrophobic mixed surface, hydrophilic and strong hydrophobic mixed surface, hydrophilic surface) at 200 K. The kinetic energy of fluid atoms and the interaction energy between Pt and fluid atoms were employed to understand the evaporation process. The vapor film boiling was observed in the systems with the mole fraction of Ar to be 100%, 75% and 50%. This leads to the heat flux significantly decreasing and heat transfer deterioration. The addition of Kr atoms will alleviate and prevent vapor film boiling of Ar atoms. Besides, the more the mole fraction of Kr in the system, the less possibility of Kr atoms can evaporate from the evaporation region. The strong hydrophobic surface would lead to the bubble generated earlier than weak hydrophobic surface. And the earlier generated bubble on hydrophilic and strong hydrophobic mixed surface will enhance the evaporation process than that on hydrophilic and weak hydrophobic mixed surface.

Optimisation of fully depleted SiGe channel with raised source/drain buried oxide nMOSFET

A fully depleted silicon-germanium (SiGe) n-channel heterojunction MOSFET with raised buried oxide in the source/drain is reported under the consideration that channel is made of SiGe and source/drain regions is made of silicon (Si). Due to the raised buried oxide source/drain region, it provides better current due to the improvement of mobility in the channel region and also reduce the surface scattering effects. Bandgap engineering has been done to improve the electrical behaviour of the device. Simulation work for different parameters on the device has been carried out and presented in the paper. The electrical characteristics of the proposed device are optimised by varying the device dimensions. Effect of mole fraction on threshold voltage (VTH), Subthreshold swing (SS), ION and IOFF current ratio is analysed. It is observed that due to presence of SiGe channel and the raised source/drain, the proposed device shows enhancement in electrical characteristics. A CMOS inverter through proposed device has been implemented and the effect of mole fraction on its characteristic is reported. Average delay increases as mole fraction increases.

Optimisation of fully depleted SiGe channel with raised source/drain buried oxide nMOSFET

A fully depleted silicon-germanium (SiGe) n-channel heterojunction MOSFET with raised buried oxide in the source/drain is reported under the consideration that channel is made of SiGe and source/drain regions is made of silicon (Si). Due to the raised buried oxide source/drain region, it provides better current due to the improvement of mobility in the channel region and also reduce the surface scattering effects. Bandgap engineering has been done to improve the electrical behaviour of the device. Simulation work for different parameters on the device has been carried out and presented in the paper. The electrical characteristics of the proposed device are optimised by varying the device dimensions. Effect of mole fraction on threshold voltage (VTH), Subthreshold swing (SS), ION and IOFF current ratio is analysed. It is observed that due to presence of SiGe channel and the raised source/drain, the proposed device shows enhancement in electrical characteristics. A CMOS inverter through proposed device has been implemented and the effect of mole fraction on its characteristic is reported. Average delay increases as mole fraction increases.

Effect of mole fraction, doping concentration and gate length on the electrical characteristics of nanoelectronic High Electron Mobility Transistor

Abstract In this work, we have optimized the device structure to achieve a maximum drain current of Nanoelectronic AlGaN/GaN single-heterojunction high electron mobility transistors (HEMTs) by the variations of mole fraction, doping concentration and gate length, using the SILVACO-ATLAS software tool. The drain current increases at higher aluminium mole fraction of AlGaN nano-layer. The drain current increases at higher doping concentration of AlGaN nano-layer. The drain current reduces at higher gate length of HEMTs. The conduction band engineering in terms of quantum wells is investigated in detail by involving the Bose-Einstein expression. The simulation results of this work are supported by the available previous experimental results and analytical modelling. This work will be useful to fabricate the AlGaN/GaN HEMTs experimentally for bioengineering applications.

Theoretical study of strain-dependent optical absorption in a doped self-assembled InAs/InGaAs/GaAs/AlGaAs quantum dot.

A detailed theoretical study of the optical absorption in doped self-assembled quantum dots is presented. A rigorous atomistic strain model as well as a sophisticated 20-band tight-binding model are used to ensure accurate prediction of the single particle states in these devices. We also show that for doped quantum dots, many-particle configuration interaction is also critical to accurately capture the optical transitions of the system. The sophisticated models presented in this work reproduce the experimental results for both undoped and doped quantum dot systems. The effects of alloy mole fraction of the strain controlling layer and quantum dot dimensions are discussed. Increasing the mole fraction of the strain controlling layer leads to a lower energy gap and a larger absorption wavelength. Surprisingly, the absorption wavelength is highly sensitive to the changes in the diameter, but almost insensitive to the changes in dot height. This behavior is explained by a detailed sensitivity analysis of different factors affecting the optical transition energy.

THE EFFECTS OF INLET AIR QUANTITY AND INLET OXYGEN MOLE FRACTION ON THE COMBUSTION AND FLUID FLOW IN A SULFUR RECOVERY UNIT THERMAL REACTOR

Owing to the high temperature inside a sulfur recovery unit (SRU) thermal reactor, detailed experimental measurements are difficult. In the author’s previous studies, several methods have been assessed to resolve the abnormality of the SRU thermal reactor under high temperature operation. This paper presents a new easier and more economical method. The effects of inlet air quantity and inlet O2 mole fraction on the combustion and fluid flow in a SRU thermal reactor are investigated numerically. The flow field temperature, S2 recovery, H2S mole fraction, and SO2 emissions are analyzed. This paper provides a guideline for adjusting the inlet air quantity and the inlet O2 mole fraction to reduce the high temperature inside a thermal reactor and to ensure an acceptable sulfur recovery.

Comparative Study of the Characteristics in Strained Al<sub>x</sub>In<sub>y</sub>Ga<sub>(1-x-y)</sub>N/InGaN and Al<sub>x</sub>In<sub>y</sub>Ga<sub>(1-x-y)</sub>N/GaN Heterostructures

The paper emphasized on different characteristics AlInGaN/InGaN and AlInGaN/GaN heterostructures for enhancing the device performance. Effect of changing mole fraction in bandgap, strain, polarization have been investigated. Amount of sheet charge density created on the heterointerfaces of AlInGaN /InGaN and AlInGaN/GaN heterostructures have been calculated. It has been observed that with the increment of Indium mole fraction and the decrement of Aluminium mole fraction, the total polarization increases hence larger 2DEG and sheet charge density is created.

Effect of the Ge Mole Fraction on the Electrical Characteristics of Single and Dual Channel Vertical Strained SiGe Impact Ionization MOSFET (VESIMOS)

The effect of the Ge mole fraction in a Si1-xGex on single and dual channel Vertical Strained SiGe Impact Ionization MOSFET was successfully analyzed. It is found that the threshold voltage, breakdown voltage and sub-threshold slope of the devices was affected by the presence of the Germanium. A better performance in sub-threshold voltage of the devices was obtained for dual channel VESIMOS compared to single channel VESIMOS with a suitable amount of Germanium. Germanium has high and symmetric impact ionization rates to ensure the transition from OFF state to ON state is abrupt. With the appearance of the SiGe layer in the devices, has an advantage of the mobility enhancement of carriers in the devices operation. With the improvement of the Ge composition, it could transform VESIMOS into a new paradigm of devices which applicable to nanoelectronics with better electrical characteristics.

Numerical and experimental investigation on the performance of lean burn catalytic combustion for gas turbine application

This manuscript presents our numerical and experimental results regarding the performance characteristics of lean burn catalytic combustion for gas turbine application. The reactant transport was assumed to be controlled by both bulk diffusion as well as surface kinetics, implemented by means of an approximate reaction rate equation and empirical coefficients to incorporate reaction mechanism. Experimental and numerical results were compared to examine the effects of methane mole fraction, inlet temperature, operating pressure, velocity and hydrogen species on combustion intensity. The results indicate that inlet temperature is the most significant parameter that impacts operation of the catalytic combustor and the most effective methods for improving the methane conversion are increasing the inlet temperature and increasing the methane mole fraction. Simulations from 1D heterogeneous plug flow model can capture the trend of catalytic combustion and describe the behavior of the catalytic monolith in detail. The addition of hydrogen will provide heat release by the exothermic combustion reaction so that the reactants reach a temperature at which methane oxidation can light-off.

Unique model of polarization engineered AlGaN/GaN based HEMTs for high power applications

In this paper, a novel source/drain Schottky contact technology AlGaN/GaN HEMT device is designed and modelled. Based on this concept, effect of mole fraction in three different HEMT devices is studied using the unique mathematical model. An optimized Al0.2Ga0.8N/GaN HEMT shows an excellent improvement in sheet carrier density and breakdown voltage. Break down voltage (BV) is one of the major concerns in the present day High Electron Mobility Transistor device (HEMT). The proposed device with Lgd of 5μm shows a breakdown voltage of 320V, which is in good agreement with experimental data. In addition to this, drain current, transconductance and frequency is also modelled and simulated using TCAD. Hence Schottky based AlGaN/GaN HEMT is one of the promising candidates for high power applications.

Progress on the Numerical Calculation of Electrical Characteristics of Strained SiGe Channel P-MOSFET

Recent progress in the computer simulation of strained SiGe channel p-MOSFET performance is reviewed. The electrical characteristics of strained SiGe channel p-MOSFET, such as threshold voltage, subthreshold characteristics, output characteristics, transconductance, quasistaticC-Vcharacteristics and transfer characteristics, and the effects of Ge mole fraction on electrical characteristics, are well discussed. Finally, the development of strained SiGe channel p-MOSFET is prospected.

Numerical optimization of two-dimensional electron gas in Mg x Zn1− x O/ZnO heterostructures (0.10 < x < 0.30)

One-dimensional, self-consistent Schrödinger–Poisson equations are solved for the wurtzite Mg x Zn1− x O/ZnO heterostructure (0.1 < x < 0.3). For the [] orientation, a polarization-induced two-dimensional electron gas (2DEG) is found to be populated at the pseudo-triangular quantum well (QW) that is formed at Mg x Zn1− x O/ZnO interface. The effects of different Mg mole fractions and different Mg x Zn1− x O barrier thicknesses on the band structure, charge densities and electron probability densities are calculated. Formation of a second subband is found to never exist under strained conditions for the investigated structures. By including the effect of QW width on mobility of the 2DEG, a structure with x = 0.15 and a barrier thickness of 22 nm has been suggested for high temperature applications.