J. Yang, L. Lolle, J. Poll; Theory of the high frequency wind in interaction‐induced spectra, AIP Conference Proceedings, Volume 216, Issue 1, 1 December 1990,
J. Yang, L. Lolle, J. Poll; Theory of the high frequency wind in interaction‐induced spectra, AIP Conference Proceedings, Volume 216, Issue 1, 1 December 1990,
The long-term objective of this work is to produce a stable, efficient amorphous Si (a-Si) solar cell by a safe and inexpensive method. A process of reactive evaporation in a silane ambient was developed. This techniq...
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The long-term objective of this work is to produce a stable, efficient amorphous Si (a-Si) solar cell by a safe and inexpensive method. A process of reactive evaporation in a silane ambient was developed. This technique permits the fabrication of "intrinsic-like" a-Si:H. p-Type and n-type samples (carrier type was confirmed by Seebeck measurements) were prepared by the coevaporation of boron or reactive evaporation in a phosphorus ambient. The intrinsic-like samples have a room temperature conductivity of about 2 × 10−12 S cm−1, high temperature activation energies of 0.9 eV, and optical bandgaps near 1.8 eV. An all-amorphous Si:H pin diode was fabricated using this reactive evaporation process. The device consists of a tantalum contact, 20 – 40 nm of phosphorus doped a-Si:H, 300 – 400 nm of undoped a-Si:H, 20 – 40 nm of boron doped a-Si:H, and another tantalum contact.
I review the status of the constituent quark model. I begin by showing that phenomenological heavy-quark potentials are in qualitative agreement with potentials calculated from first principles using the techniques of...
I review the status of the constituent quark model. I begin by showing that phenomenological heavy-quark potentials are in qualitative agreement with potentials calculated from first principles using the techniques of lattice QCD. I next argue that it is reasonable to extend the constituent quark model to light-quark systems where nonrelativistic approximations are no longer valid. We find that both mesons and baryons can be described in a «relativized» quark model which suggests a connection between the quark model and the fundamental theory, QCD. In the final section I review how the quark model is applied to multiquark systems. Using the example of six-quark systems it is seen that the qualitative features of nuclear physics can be derived from the quark model.
We present the classical and quantum versions of collision induced absorption spectra for three exactly solvable 1-D models, and obtain the asymptotic behaviour at high frequency. It is found that the quantum spectra ...
We present the classical and quantum versions of collision induced absorption spectra for three exactly solvable 1-D models, and obtain the asymptotic behaviour at high frequency. It is found that the quantum spectra fall off more slowly than the classical, and for realistic systems, they both fall off more slowly than exponential. An improved version of the Landau-Lifshitz WKB method is suggested as a numerically viable method for calculating the high frequency wing in quantum spectra and is tested on the exactly solvable models. The error is found to be negligible in two models and tolerable in the third model, even for the least classical system. Our discussion of an extension of the method using exact wavefunctions increases its scope beyond the collision induced absorption problem.
Peaks in the 20–40 keV region of Si(Li) X-ray spectra exhibit pronounced low-energy tailing due to Compton scattering of X-rays en route to the detector. An analytic description of this tailing is proposed and tested...
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Peaks in the 20–40 keV region of Si(Li) X-ray spectra exhibit pronounced low-energy tailing due to Compton scattering of X-rays en route to the detector. An analytic description of this tailing is proposed and tested using proton-induced X-rays from thick targets. In the PIXE context this provides more accurate extraction of peak intensity and a better description of the matrix background.
An exact but computationally economical treatment of secondary fluorescence in PIXE is presented. A major difference from previous treatments is the use of Subshell photoelectric absorption cross sections as opposed t...
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An exact but computationally economical treatment of secondary fluorescence in PIXE is presented. A major difference from previous treatments is the use of Subshell photoelectric absorption cross sections as opposed to total cross sections and absorption edge jump ratios. Numerical comparisons show significant predictive differences relative to previous work and some simple experimental tests are described. The first calculations to date of tertiary fluorescence enhancement are presented and this effect is shown to be small.
A differential method for measuring the thickness of aluminum foils used as X-ray absorbers in thick-target PIXE analysis is described. It involves the change in K β K α X-ray intensity resulting from transmission t...
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A differential method for measuring the thickness of aluminum foils used as X-ray absorbers in thick-target PIXE analysis is described. It involves the change in K β K α X-ray intensity resulting from transmission through the foil and provides better acc than direct X-ray attenuation measurements.
Various semi-empirical schemes for generating x-ray attenuation coefficients, μ/ρ, devised primarily for use in electron probe microanalysis, are considered for application in the PIXE analysis of thick specimens wh...
Various semi-empirical schemes for generating x-ray attenuation coefficients, μ/ρ, devised primarily for use in electron probe microanalysis, are considered for application in the PIXE analysis of thick specimens where the relevant x-ray energy region is 1–40 keV. Using selected high-accuracy experimental data, it is shown that current theoretical values of μ/ρ agree better with the data than do the various schemes. The errors transmitted into PIXE analysis by use of the theoretical values are estimated, and a new parameterization of these values suitable for microcomputer use is justified and tested.
The first full account of the guelph software for fitting PIXE spectra and deriving elemental concentrations is presented. The entire data base has been updated since the program was first reported. Some of the less s...
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The first full account of the guelph software for fitting PIXE spectra and deriving elemental concentrations is presented. The entire data base has been updated since the program was first reported. Some of the less standard procedures used are discussed in detail; these include the approach to error estimation, the ability to define an element in a thick specimen as a bulk or surface constituent, the ability to redefine the principal line of an element's X-ray spectrum and safeguards against premature elimination from the fit of elements having low concentration. In addition to peak areas, element concentrations and corresponding errors, the program provides limits of detection and a measure of the depth analysed for each element.
It has been shown that it is possible to produce low-resistivity (10 2 ω cm) device-grade films of polycrystalline Zn 3 P 2 by the hot-wall technique and to produce low-leakage diodes (rectification ratio greater tha...
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It has been shown that it is possible to produce low-resistivity (10 2 ω cm) device-grade films of polycrystalline Zn 3 P 2 by the hot-wall technique and to produce low-leakage diodes (rectification ratio greater than 100) by evaporating magnesium or aluminium dots onto the resulting Zn 3 P 2 films. I–V and C–V measurements have been shown to be in qualitative agreement with the metal/ insulator/semiconductor model of Chattopadhyay and A.N. Daw, Solid State Electron., 29 (1986) 555.) which involves a patchy oxide between the metal and semiconductor regions. If the difference between the Fermi level and the valence band edge for our polycrystalline Zn 3 P 2 films is assumed to be the same as that found by Szatkowski and Sieranski for single-crystal Zn 3 P 2 (J. Szatkowski and K. Sieranski, Solid State Electron., 31 (1988) 257.) it is shown that it is possible to determine values of C 2 and δ p /δ, parameters entering the model of Chattopadhyay and Daw. The C–V results on the Mg/Zn 3 P 2 and Al/Zn 3 P 2 diodes can be interpreted as giving values for the carrier concentration N A in the Zn 3 P 2 that differ by a factor of 11, and some possible reasons for this are examined.
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