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Wyszukujesz frazę "Christensen, N." wg kryterium: Autor


Wyświetlanie 1-8 z 8
Tytuł:
ZnS/ZnSe Superlattices under Pressure
Autorzy:
Gorczyca, I.
Christensen, N. E.
Powiązania:
https://bibliotekanauki.pl/articles/1929746.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.25.Tn
73.20.Dx
Opis:
Self-consistent linear muffin-tin orbital method is used to calculate the band structure of ZnS/ZnSe (001) strained-layer superlattice and investigate the influence of hydrostatic pressure on the valence band offset (VBO). Three different strain modes corresponding to various values of the relative thicknesses of both materials are considered. A I → II type conversion associated with the conduction-band crossover between the ZnSe well and ZnS barrier layers is found in agreement with recent experimental data.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 753-756
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calculations of Native Defects in Cubic AlN
Autorzy:
Gorczyca, I.
Svane, A.
Christensen, N. E.
Powiązania:
https://bibliotekanauki.pl/articles/1950799.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ey
71.55.Eq
Opis:
We have studied the electronic structure of native defects in cubic AlN. N and Al vacancies, antisites and interstitials are investigated in different charge states. We have performed first-principles calculations based on density-functional theory, using two methods. The first one is the Green-function technique based on the linear muffin-tin orbital method in the atomic-spheres approximation. Defects considered are all ideal substantial ones, i.e., no relaxation of the neighboring atoms is allowed for in this method. The results for aluminium vacancy and for nitrogen antisite are compared to the calculations using supercell approach and the full-potential linear muffin-tin orbital (the second method) with lattice relaxation included.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 793-796
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calculations of Point Defects in AlN and GaN; Lattice Relaxation Effects
Autorzy:
Gorczyca, I.
Christensen, N. E.
Svane, A.
Powiązania:
https://bibliotekanauki.pl/articles/1968105.pdf
Data publikacji:
1997-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ey
71.55.Eq
Opis:
Native defects (vacancies, antisites and interstitials) and substitutional impurities (Mg, Zn, and C) in cubic GaN and AlN are studied by means of ab initio theoretical calculations. We examine the energetic positions of the defect levels and lattice relaxations effects. Whereas small relaxations are found in the case of vacancies, the calculations predict that large atomic displacements are associated with antisites. We also discuss the metastable behavior of the nitrogen antisite.
Źródło:
Acta Physica Polonica A; 1997, 92, 4; 785-788
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure and Optical Properties of GaAs$\text{}_{1-x}$N$\text{}_{x}$ and Ga$\text{}_{1-x}$B$\text{}_{x}$As Alloys
Autorzy:
Gonzalez Szwacki, N.
Bogusławski, P.
Gorczyca, I.
Christensen, N. E.
Svane, A.
Powiązania:
https://bibliotekanauki.pl/articles/2035594.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Nr
78.20.Bh
Opis:
The electronic band structure of GaAs$\text{}_{1-x}$N$\text{}_{x}$ (x=0.016 and 0.031) and Ga$\text{}_{1-x}$B$\text{}_{x}$As (x= 0.031) is studied by ab initio calculations using a supercell approach. Based on ab initio calculations and group theory we present a comprehensive analysis of the electronic structure of GaAs:N and GaAs:B alloys. In particular, we study the effective mass of conduction electrons in GaAs:N as a function of pressure and the Fermi energy. We find that the lowest conduction band is strongly non-parabolic, which leads to an increase in the effective mass with the electron energy. The rate of the increase is enhanced by the hydrostatic pressure. Theoretical results are compared to experimental data, and a qualitative agreement is found.
Źródło:
Acta Physica Polonica A; 2002, 102, 4-5; 633-641
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Band Structure and Refractive Index of Gallium Nitride Under Pressure
Autorzy:
Perlin, P.
Gorczyca, I.
Suski, T.
Teisseyre, H.
Grzegory, I.
Christensen, N.
Powiązania:
https://bibliotekanauki.pl/articles/1891272.pdf
Data publikacji:
1991-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.25.Tn
78.20.Ci
Opis:
The effect of hydrostatic pressure on direct gap and refractive index of GaN is investigated up to 5.5 GPa. Band structure of GaN is calculated by Linear Muffin-Tin Orbitals (LMTO) method for different values of pressure. Resulting pressure coefficient of the main gap and of the refractive index are in a good agreement with the experimental ones.
Źródło:
Acta Physica Polonica A; 1991, 80, 3; 421-424
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Band Structure of In$\text{}_{x}$Ga$\text{}_{1-x}$N under Pressure
Autorzy:
Gorczyca, I.
Christensen, N. E.
Svane, A.
Laaksonen, K.
Nieminen, R. M.
Powiązania:
https://bibliotekanauki.pl/articles/2047377.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
71.55.Eq
71.20.-b
Opis:
The electronic band structures of zinc-blende In$\text{}_{x}$Ga$\text{}_{1-x}$N alloys with x varying from 0.03 to 0.5 are examined within the density functional theory. The calculations, including structural optimizations, are performed by means of the full-potential linear muffin-tin-orbital and pseudopotential methods. The effects of varying the composition, x, and of applying external pressure are studied. A composition-dependent band gap bowing parameter in the range of 1.6-2 eV is obtained. A strong nonlinearity in the composition dependence of the pressure coefficient of the band gap is found.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 203-208
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
III-V Semiconducting Nitrides Energy Gap under Pressure
Autorzy:
Perlin, P.
Gorczyca, I.
Teisseyre, H.
Suski, T.
Litwin-Staszewska, E.
Porowski, S.
Grzegory, I.
Christensen, N. E.
Powiązania:
https://bibliotekanauki.pl/articles/1921585.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.25.Tn
Opis:
In this paper we present overview of our recent experimental and theoretical results concerning electronic band structure of III-V nitrides under pressure. It is shown here that the pressure coefficients of the direct gap for studied nitrides are surprisingly small. To describe tendency in changes of the gap with pressure we use a simple empirical relation.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 674-676
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shape optimization of a loudspeaker diaphragm with respect to soun directivity properties
Autorzy:
Christensen, S.
Olhoff, N.
Powiązania:
https://bibliotekanauki.pl/articles/206828.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
akustyka
metoda elementów brzegowych
metoda elementów skończonych
acoustics
boundary element method
finite element method
loudspeaker sound directivity
optimum design
Opis:
This paper presents a novel method for optimizing the directivity of the sound emission from the diaphragm of an electro dynamic loudspeaker. The analysis of the diaphragm is performed by finite element analysis of the structural dynamic behaviour and using the boundary element method for the acoustic analysis. Through optimization of a dead mass distribution on the diaphragm, or of the shape of the mid-surface of the diaphragm, it has been possible to improve its directivity properties for sound emission. Several illustrative examples are presented at the end of the paper.
Źródło:
Control and Cybernetics; 1998, 27, 2; 177-198
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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