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1
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ZnS/ZnSe Superlattices under Pressure

100%
Gorczyca I., Christensen N.
Acta Physica Polonica A
|
1993
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vol. 84
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issue 4
753-756
EN
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.
2
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Calculations of Native Defects in Cubic AlN

81%
Gorczyca I., Svane A., Christensen N.
|
EN
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.
3
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Electronic Band Structure of In_xGa_{1-x}N under Pressure

71%
Gorczyca I., Christensen N., Svane A., Laaksonen K., Nieminen R.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
203-208
EN
The electronic band structures of zinc-blende In_xGa_{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.
4
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Electronic Structure and Optical Properties of GaAs_{1-x}N_x and Ga_{1-x}B_xAs Alloys

71%
Gonzalez Szwacki N., Bogusławski P., Gorczyca I., Christensen N., Svane A.
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issue 4-5
633-641
EN
The electronic band structure of GaAs_{1-x}N_x (x=0.016 and 0.031) and Ga_{1-x}B_xAs (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.
5
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Band Structure and Refractive Index of Gallium Nitride Under Pressure

61%
Perlin P., Gorczyca I., Suski T., Teisseyre H., Grzegory I., Christensen N.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
421-424
EN
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.
6
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III-V Semiconducting Nitrides Energy Gap under Pressure

52%
Perlin P., Gorczyca I., Teisseyre H., Suski T., Litwin-Staszewska E., Porowski S., Grzegory I., Christensen N.
Acta Physica Polonica A
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1992
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vol. 82
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issue 4
674-676
EN
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.
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