scholarly journals Квантовый транспорт в полупроводниковом нанослое с учетом поверхностного рассеяния носителей заряда

2021 ◽  
Vol 55 (9) ◽  
pp. 789
Author(s):  
И.А. Кузнецова ◽  
О.В. Савенко ◽  
Д.Н. Романов
Keyword(s):  
Energy Surface ◽  
Chemical Potential ◽  
Silicon Layer ◽  
Transport Processes ◽  
Charge Carriers ◽  
Axis Parallel ◽  
Ellipsoid Of Revolution ◽  
De Broglie Wavelength ◽  
Analytical Expressions ◽  
Degenerate Electron Gas

The problem of the conductivity of a thin conductive nanolayer is solved taking into account the quantum theory of transport processes. The layer thickness can be comparable to or less than the de Broglie wavelength of charge carriers. The constant-energy surface has the form of an ellipsoid of revolution with the main axis parallel to the layer plane. Analytical expressions are obtained for the conductivity tensor components as a function of dimensionless thickness, chemical potential, ellipticity parameter, and surface roughness parameters. The conductivity analysis for the limiting cases of a degenerate and non-degenerate electron gas are conducted. The results are compared with known experimental data for a silicon layer.

scholarly journals XXIV Международный симпозиум Нанофизика и наноэлектроника", Нижний Новгород, 10-13 марта 2020 г. Влияние граничных условий на высокочастотную электропроводность тонкого проводящего слоя в продольном магнитном поле

2020 ◽  
Vol 54 (9) ◽  
pp. 846
Author(s):  
И.А. Кузнецова ◽  
О.В. Савенко ◽  
П.А. Кузнецов
Keyword(s):  
High Frequency ◽  
Longitudinal Magnetic Field ◽  
Chemical Potential ◽  
Theoretical Calculations ◽  
Mean Free Path ◽  
Thin Metal Film ◽  
Charge Carriers ◽  
Field Frequency ◽  
Electric Field Frequency ◽  
Degenerate Electron Gas

The problem of the high-frequency conductivity of a thin conductive layer in a longitudinal magnetic field is solved in terms of kinetic approach taking into account diffuse-mirror boundary conditions. Specularity coefficients of layer surfaces are assumed to be different. An analytical expression is derived for dimensionless integral conductivity as a function of dimensionless parameters: layer thickness, electric field frequency, magnetic induction, chemical potential and surface specularity coefficients. The limiting cases of a degenerate and non-degenerate electron gas are considered. A comparative analysis of theoretical calculations with experimental data is carried out. The method to determine specularity coefficients and mean free path of charge carriers from the longitudinal magnetoresistance of a thin metal film is illustrated.

Tc of intermediate coupling superconductors with a variable electronic density of states (EDOS)

1983 ◽  
Vol 61 (2) ◽  
pp. 212-219
Author(s):  
M. Ashraf ◽  
J. P. Carbotte
Keyword(s):  
Density Of States ◽  
Chemical Potential ◽  
Present Calculation ◽  
Zero Temperature ◽  
Intermediate Coupling ◽  
Electronic Density ◽  
Electronic Density Of States ◽  
Dimensionless Ratio ◽  
Arbitrary Position ◽  
Analytical Expressions

Using the model of Leavens and Carbotte for intermediate coupling superconductors, we have derived and evaluated analytical expressions for the critical temperature Tc, and the zero temperature gap Δ0 of those superconductors with a variable electronic density of states (EDOS). EDOS is given by a Lorentzian peak superimposed on a constant background with the chemical potential falling at some arbitrary position within the peak. The most significant modifications occur for a narrow Lorentzian with the peak close to the Fermi level. The value of the dimensionless ratio 2Δ0/kBTc remains close to the Bardeen–Cooper–Schrieffer (BCS) value of 3.53. Also, the present calculation compares very favourably with a previous exact calculation.

Analysis of a Tunable CMOS-compatible Multilayer Waveguide Structure for Dual Polarizer-modulator Operation

2021 ◽  
Author(s):  
Renan Silva Santos ◽  
Maria A. G. Martinez
Keyword(s):  
Chemical Potential ◽  
Extinction Ratio ◽  
Silicon Layer ◽  
Individual Case ◽  
Waveguide Structure ◽  
Potential Range ◽  
Figures Of Merit ◽  
Silicon Waveguide ◽  
The One ◽  
Better Than

Abstract A multilayer structure using graphene on a silicon waveguide is introduced and optimized to operate as a tunable TE-pass polarizer at 1310 nm or 1550 nm, a tunable TE/TM modulator at 1310 nm or 1550 nm, and a dual operation as a modulator at 1310 nm and a polarizer at 1550 nm. The analysis is based on the waveguide structure modal loss, the 2D graphene layer optical properties and its dependency on the applied chemical potential. The optimization is done by varying waveguide height and choosing the one with best figures of merit for each individual case and for the dual operation, the value that causes the least impairment overall is chosen. The polarizer tunability at 1310 nm or 1550 nm is attainable setting the applied chemical potential range from 0.55–0.65 eV or 0.45–0.55 eV, respectively. For the modulator tunability at 1310 nm or 1550 nm, the applied chemical potential range from 0.45–0.55 eV or 0.35–0.45 eV, respectively. The optimized waveguide silicon layer around 210 nm guarantees an extinction ratio better than 0.056 dB/µm for the polarizer and better than 0.045/0.133 dB/µm for the TE/TM modulator at 1310 nm, and better than 0.034 dB/µm for polarizer and better than 0.053/0.137 dB/µm for TE/TM modulator at 1550 nm. Further, the setting the chemical potential range at 0.45–0.55 eV, allows dual polarizer-modulator operation, with the modulator operating at 1310 nm and the polarizer operating at 1550 nm, presenting an extinction ratio better than 0.045 dB/µm and 0.034 dB/µm respectively. In all situations analyzed, insertion loss is lower than 0.007 dB/µm. The advantage of the structure in comparison with other similar devices relies in its versatility to operate as both modulator and polarizer, in different wavelengths, via a proper choosing of the applied chemical potential.

Effects of Interfacial Phenomena and Conduction on an Evaporating Meniscus

2007 ◽  
Author(s):  
Peter C. Wayner
Keyword(s):  
Heat Flux ◽  
Free Energy ◽  
Temperature Field ◽  
Phase Change ◽  
Slip Velocity ◽  
Chemical Potential ◽  
Transport Processes ◽  
Liquid Pressure ◽  
Thickness Profile ◽  
Concentration Changes

An overview of some of the theoretical models describing the effects of chemical potential, excess free energy, free energy gradient, film thickness profile, temperature profile, superheat, thermal conduction, concentration gradient, velocity profile, slip velocity, apparent contact angle, and kinetic theory on the phase change heat transfer processes in an evaporating meniscus are presented. The relative importance of the parameters is demonstrated. Experimental techniques and confirming experimental data are also presented. In essence, the microscopic thickness profile of the evaporating meniscus is measured optically to obtain the details of the liquid pressure field and modeled to give the fluid flow rate and the evaporative heat flux. The macroscopic temperature field of the substrate is measured and numerically modeled to give the microscopic temperature field and a complementary calculation of the evaporative heat flux. For closure, the values of the slip velocity and concentration change on evaporation need to be correctly assumed. The interfacial transport processes are very sensitive to small interfacial temperature and concentration changes, which are difficult, if not impossible, to measure directly. However, the liquid pressure gradients can be directly measured. The effects of the interacting phenomena on the phase change processes are demonstrated using these complementary experimental-modeling procedures. The processes are found to be very complex and simple modeling/experiments can only confirm the general phenomena and give insight.

scholarly journals Researches on physical geology.—Part I. The figure and primitive formation of the earth

1851 ◽  
Vol 5 ◽  
pp. 659-659
Keyword(s):  
Chemical Changes ◽  
Fluid Mass ◽  
General Properties ◽  
The Earth ◽  
Figure Of The Earth ◽  
Ellipsoid Of Revolution ◽  
The Law ◽  
Physical Geology ◽  
Analytical Expressions ◽  
Different Parts

The author’s investigations of the figure of the earth proceed on the hypothesis of its having originally been a heterogeneous fluid mass, possessing only such general properties as those which have been established for fluids; and independently of the supposition, with which the theory has generally been complicated, that the vo­lume of the entire mass, and the law of the density of the fluid, have suffered no change in consequence of the solidification of a part of that fluid. Assuming the figure of the mass to be an ellipsoid of revolution, the author obtains general analytical expressions for its ellipticity, and for the variation of gravity at its surface. He gives a general sketch of the consequences that may result from the im­proved hypothesis of the primitive figure of the earth, to physical geology, that is, to the changes occurring upon the external crust of the earth during the process of its solidification, resulting both from calorific and chemical changes taking place among its different parts, and giving rise to a process of circulation throughout the fluid por­tions of the mass. The present memoir is only the first of a series which the author announces it is his intention to communicate to the Society on the same subject.

Anionic and Cationic Diffusion in Ionic Conducting Oxides

2005 ◽  
Vol 237-240 ◽  
pp. 843-848 ◽  
Author(s):  
Georgette Petot-Ervas ◽  
C. Petot ◽  
Jean Marc Raulot ◽  
J. Kusinski
Keyword(s):  
Chemical Potential ◽  
Potential Gradient ◽  
Transport Processes ◽  
Electrical Field ◽  
Experimental Procedure ◽  
Conducting Oxides ◽  
Self Diffusion ◽  
Ionic Conducting ◽  
Applied Electrical Field

This paper concerns an analysis of the transport processes at high temperature in anionic conducting oxides subjected to a chemical potential gradient or an applied electrical field. The general equations are given. The principle of the cationic kinetic demixing under a “generalized“ thermodynamical potential gradient is reviewed. Experimental results obtained with yttria-doped zirconia are reported. An experimental procedure for the determination of the oxygen diffusion coefficient in ionic and semiconducting oxides is also described. The results obtained with yttriastabilized zirconia are compared to both self diffusion and conductivity data. This has allowed us to obtain information concerning the defect structure.

Particle Entropies and Entropy Quanta. I. The Ideal Gas

2000 ◽  
Vol 214 (2) ◽  
Author(s):  
Helmuth W. Zimmermann
Keyword(s):  
Chemical Potential ◽  
Boltzmann Distribution ◽  
Ideal Gas ◽  
Einstein Condensation ◽  
Translational Energy ◽  
Quantum Numbers ◽  
De Broglie Wavelength ◽  
Bose Einstein ◽  
Particle Statistics ◽  
The Ideal

We consider an ideal gas of monatomic independent particles, which is enclosed in a cubic box. At temperature T the particles are in thermal equilibrium. All relevant properties of the gas can be deduced from the particle statistics on the assumption that each particle of the ensemble has the particle entropy σ = ε/T = ka. ε is the translational energy of the particle. The non-dimensional number a measures the particle entropy σ in multiples of the Boltzmann constant k, which acts as an atomic entropy unit. a obeies an eigenvalue equation and satisfies boundary conditions. Eigenvalues and eigenfunctions are determined by the translational quantum numbers. Using particle entropies it is easy to calculate the Bose-Einstein and the Boltzmann distribution; and in combination with the density function we immediately get the internal energy E and the Helmholtz free energy F, the total entropy S, the chemical potential μ, the equation of state of the ideal gas at ordinary temperatures and at low temperatures near absolute zero, inclusively Bose-Einstein condensation. Entropy quanta are used to introduce the temperature into the equations of statistical thermodynamics and to calculate the thermal and the actual de Broglie wavelength at temperature T.

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