Quasi-static Characteristics Research Articles

Unpinned GaAs MOS capacitors and transistors

Metal-oxide-semiconductor (MOS) capacitors and field-effect transistors (MOSFETs) in the GaAs semiconductor system using an unpinned interface are described. The structures utilize plasma-enhanced chemical-vapor deposition (PECVD) for the silicon-dioxide insulator on GaAs that has been terminated with a few monolayers of silicon during growth by molecular beam epitaxy. Interface densities in the structures have been reduced to approximately 10/sup 12/ cm/sup -2/.eV/sup -1/. High-frequency characteristics indicate strong inversion of both p-type and n-type GaAs. The excellent insulating quality of the oxide has allowed demonstration of quasi-static characteristics. MOSFETs operating in depletion mode with a transconductance of 60 mS/mm at 8.0- mu m gate lengths have been fabricated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Reversible interaction of hydrogen with thin layers of thermally grown silicon dioxide

Some effects of hydrogen on the electrical properties of Pd-metal-thin (≊10 nm) oxide-silicon capacitors are reported. High-frequency (1 MHz) and quasistatic capacitance voltage curves are measured at 100 °C as a function of hydrogen partial pressure in a background atmosphere of 20% O2/Ar. Besides the standard hydrogen-induced shift of the capacitance-voltage characteristics we find: (1) an increase in the accumulation capacitance with increasing hydrogen partial pressure, and (2) a nonmonotonic increase in the quasistatic capacitance minimum with increasing hydrogen pressure. The relative increase in the accumulation capacitance is shown to be related to the square of the hydrogen-induced voltage shift (and hence to the square of the concentration of hydrogen atoms at the Pd-SiO2 interface). We discuss our findings, based on existing hydrogen-silicon dioxide models, to interpret the effects of hydrogen on the high-frequency and quasistatic capacitance characteristics.

Quasistatic capacitance of p/n junction space-charge layers by the Leibnitz rule

The Leibnitz rule of integral calculus yields a useful expression for the quasistatic capacitance versus voltage characteristic of a p/n junction space-charge layer that holds for all doping profiles and for forward as well as for reverse applied voltages. This capacitance is the sum of two components. One accounts for the incremental mobile charge within the volume of the layer. The other accounts for the incremental mobile charge at its edges.This expression enables novel analytical characterizations and interpretations of numerical solutions.

Quasistatic characteristics of slotted parallel-plate waveguides

The quasistatic characteristics of a parallel-plate waveguide with multiple slots of infinite extension in its upper plate are investigated in this paper. The analysis utilises the characteristic currents for the slots determined under the quasistatic approximation. The equivalent magnetic currents on the slots and the radiation pattern are determined when the array of slots is illuminated by a transverse electromagnetic wave incident in the waveguide, or by a transverse electric plane wave incident in the upper half-space. Analytic expressions, in the case of a single slot, are also given.

Improved feedback charge method for quasistatic C V measurements in semiconductors

A method is described for the measurement of quasistatic CV characteristics in semiconductors which offers significant advantages over previous methods. Using a small voltage step across the device under test, a displacement charge is stimulated and measured. A feedback charge measurement circuit is used, reducing the effect of several significant error terms. This technique has the advantages of higher signal-to-noise ratio at the frequencies of interest, independence of signal size from measurement time, and ease of distinction of signal charge from error currents at the time of measurement. Results consistent with those of previous techniques have been obtained on silicon MOS capacitors and other devices using steps from 10 to 100 mV and delays between step and measurement of up to 200 s. Furthermore, the method has been extended to provide additional information useful in determining whether an equilibrium measurement is obtained and in diagnosing and correcting for errors due to dc leakage currents. With this method, it is also possible to measure quasistatic capacitance at fixed bias voltage using a square-wave test signal.

Quasistatic characteristics of a coplanar waveguide with thick metal coating

Quasistatic characteristics of a coplanar waveguide with thick metal coating

Quasi-Static Characteristics of Asymmetrical and Coupled Coplanar-Type Transmission Lines

In this paper, variational expressions for the capacitances of' asymmetrical and coupled coplanar-type transmission lines are derived. The methods employed are quite general, and are useful for analyzing various types of coplanar-type transmission lines, with either an isotropic or anisotropic substrate. An accurate and efficient method of calculation is provided for the variational expressions, and some numerical results are presented.

Analysis of Asymmetric Coupled Striplines (Short Papers)

A unified method for the quasi-static and the hybrid-mode formulation of asymmetric coupled striplines is presented. Variational expressions are derived for the matrix elements, which describe the quasistatic characteristics, for the first time. A very accurate numerical method is shown and some numerical examples are presented for the different types of asymmetric coupled striplines with anisotropic substrates.

Analysis of static and quasi-static cross compound parabolic concentrators

Static and quasi-static concentrators present interesting characteristics for obtaining photovoltaic solar energy. In this work we study the characteristics of the crossed compound parabolic concentrator, formed by the intersection of two cylindrical compound parabolic concentrators (CPC). Bifacial cells are used in this concentrator as a requirement for obtaining higher concentrations. Static and quasi-static concentrators see the sun as an extended source, so a simplified source model of radiance for the sky of Madrid is used. The figures of merit of a lossless concentrator are studied and the most important parameters influencing its optical behavior are discussed. We conclude that these concentrators obtain results that lead to a decrease in the cost of photovoltaic energy.

Semiautomatic measuring device for sheets

A measuring device for testing electrical steel sheets within the frequency range 0 ≤ f ≤ 400 Hz is described. The hysteresis loop and the magnetization curve are recorded by an X-Y graphical recorder, the digitized measured values concerning the range of magnetizing force, flux density and losses (Wm -3) are displayed and printed out. The principle of data acquisition, a new-type digitizing method for dynamic hysteresis loops and the principle for measuring quasi-static characteristics are described. The configuration and reliability of the measuring device have turned out well in an in-plant research laboratory during an 18 month period.

Quasistatic Characteristics of Covered Coupled Microstrips on Anisotropic Substrates: Spectral and Variational Analysis

In this paper, expressions to compute the upper and lower bounds on true values of the even- and odd-mode capacitances of covered coupled microstrips over anisotropic substrates are obtained by using the Fourier transform and the variational approach. The method provides accurate calculation and yields the margins of error in the computation. Some examples are shown.

Unsymmetric broadside-coupled striplines

A variational expression is presented for the line capacitance of broadside-coupled striplines, whose central axes are shifted. Quasistatic characteristics are presented for isotropic and anisotropic substrates.

Quasi-Static Characteristics of Coplanar Waveguide on a Sapphire Substrate with its Optical Axis Inclined

A variational expression is presented for the line capacitance of a coplanar waveguide on a single-crystal sapphire substrate with a tilted optical axis. Numerical results are obtained by means of the Ritz procedure.

Analysis of coplanar striplines on an anisotropic substrate using Galerkin's method

AbstractA unified analysis approach is shown for obtaining the quasistatic and dispersive characteristics of coplanar Striplines on a uniaxial anisotropic substrate. Galerkin's method is adopted in the numerical calculations and the basis functions are determined systematically by use of Chebyshev polynomials with the result that solutions with desired accuracy can be obtained efficiently. In general, in coupled striplines large errors occur when the current distribution function is to be determined solely by its fringing effect. In the case of sapphire substrate, the accuracy of solution is investigated and its propagation wavelength as well as characteristic impedance are obtained and shown in graph. In these graphs the quasistatic characteristics obtained from the electrostatic approximation and the hybrid mode dispersion are compared so that a rough criterion of the error due to the electrostatic approximation can be estimated. The quasi‐static characteristics of a uniaxial anisotropic substrate line can be characterized by its effective and equivalent isotropic substrate [1]. The dispersion of the isotropic substrate line is obtained and compared with that of the original anisotropic line.

Correction to "Quasistatic characteristics of microstrip on arbitrary anisotropic substrates"

Correction to "Quasistatic characteristics of microstrip on arbitrary anisotropic substrates"

Quasi-static characteristics and magnetic properties of ferromagnetic thin film magnetoresistors

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Quasistatic characteristics of microstrip on arbitrary anisotropic substrates

An analytical approach is used to find the upper bounds of microstrip line capacitance which arbitrary anisotropic substrate. General expressions are obtained for the permittivity and the thickness of an equivalent isotropic substrate. The method is used to compute the upper and lower bounds parameters of microstrip on sapphire substrate.

Determination of power absorption in man exposed to high frequency electromagnetic fields by thermographic measurements on scale models.

When the body of man, small compared to a wavelength, is exposed to high frequency (HF) electromagnetic (EM) fields, the absorbed power density patterns and total absorbed power may be approximated by the simple superposition of the internal electric fields obtained from the quasistatic coupling characteristics of the electric and magnetic field components determined independently. These characteristics were obtained for full scale man by thermographic studies of power absorption in scale models of man exposed to fields at frequencies scaled up inversely proportional to the model size. A VHF resonant cavity was used to provide the necessary field strengths for producing measurable power absorption patterns under simulated HF exposure conditions. The results indicate that peak power absorption densities as high as 5.63 W/kg can be produced in man exposed to 10 mW/cm <R xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</R> 31 MHz radiation fields. The results show that the absorption decreases as the square of the frequency as predicted by theory for frequencies below 31 MHz.

Quasi-Static Characteristics of Microstrip on an Anisotropic Sapphire Substrate

The well-defined and repeatable electrical properties of single-crystal sapphire make it an attractive substrate material for microstrip, but its dielectric anisotropy constitutes an important design complication. This paper describes investigations into the quasi-static characteristics of single microstrip lines on sapphire substrates cut with a specified orientation. To account for anisotropy, a new permittivity parameter epsilon/sub req/ is introduced, which is a function of the Iinewidth to substrate-height ratio W/h. The variation of epsilon/sub req/ with W/h is derived by finite-difference methods. Universal curves for microstrip on correctly orientated sapphire are presented, showing 1) epsilon/sub req/, 2) the low-frequency limit of effective microstrip permittivity epsilon/sub e0/, and 3) the characteristic impedance of the line Z/sub 0/, all as functions of W/h.

An investigation of the influence of low-temperature annealing treatments on the interface state density at the Si-SiO2

The three different interface state annealing processes widely used in MOS technology have been investigated using both quasistatic capacitance-voltage measurements and MOST characteristics. It appears that annealing in a hydrogen-nitrogen and a wet nitrogen ambient is found to produce a more rapid reduction of the interface state density. The latter process is, however, more likely to cause ionic contamination of the oxide. For the achievement of the minimum interface state density with any of the three annealing treatments a 1000 degrees C anneal in dry nitrogen after oxidation is found to be essential.