Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 12

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Pressure Dependence of the Light Emission in Zinc-Blende InGaAs/GaAs and InGaN/GaN Quantum Wells

100%
Łepkowski S., Gorczyca I.
Acta Physica Polonica A
|
2009
|
vol. 116
|
issue 5
857-858
EN
We present theoretical study of the pressure coefficient of the light emission (dE_{E}/dP) in compressively strained zinc-blende InGaAs/GaAs and InGaN/GaN quantum wells, grown in a (001) direction. We investigate the contributions to dE_{E}/dP arising from (i) third-order (nonlinear) elasticity, (ii) nonlinear elasticity, originating from pressure dependence of elastic constants, and (iii) nonlinear dependence of elastic constants on composition in InGaAs and InGaN alloys. The obtained results indicate that the use of nonlinear elasticity is essential for determination of dE_{E}/dP in the strained InGaAs/GaAs and InGaN/GaN quantum wells, while the inclusion of the nonlinear dependence of elastic constants on composition of InGaAs and InGaN alloys does not improve agreement between the theoretical end experimental values of dE_{E}/dP in the considered structures.
2
Content available remote

Poisson Ratio and Biaxial Relaxation Coefficient in In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N Alloys

100%
Łepkowski S., Gorczyca I.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 5
902-904
EN
We present theoretical results showing dependence of Poisson ratio and biaxial relaxation coefficient on composition and atomic arrangement in wurtzite In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N alloys. Our calculations reveal that the Poisson ratio determined for In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N alloys subjected to a uniaxial stress parallel to the c axis of the wurtzite structure shows significant superlinear dependence on composition. The superlinear bowing in Poisson ratio is enlarged by the effect of In clustering. The biaxial relaxation coefficient determined for In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N alloys subjected to a biaxial stress in the plane perpendicular to the c axis of the wurtzite structure changes superlinearly and linearly with x in In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N, respectively. The effect of In atom clustering results in sublinear dependence of the biaxial relaxation coefficient in both In_{x}Ga_{1-x}N and In_{x}Al_{1-x}N alloys.
3
Content available remote

Structural and Elastic Properties of Wurtzite Al-Rich In_{x}Al_{1 - x}N Alloys

100%
Łepkowski S., Gorczyca I.
Acta Physica Polonica A
|
2011
|
vol. 119
|
issue 5
666-668
EN
We present theoretical study of lattice parameters and elastic constants of wurtzite Al-rich In_{x}Al_{1 - x}N (x = 0.125, 0.1875 and 0.25) alloys using self-consistent ab initio calculations with a supercell model. Two different atomic arrangements have been considered for a given x, by either distributing the In atoms as uniformly as possible over the supercell or by clustering the In atoms together in a small part of the supercell. Our calculations reveal that the a and c lattice parameters show almost linear dependence on composition for the alloys with uniform distribution of In atoms, while for the case of alloys with clustered In atoms the c lattice parameter deviates from linearity quite significantly. For the alloys with clustered In atoms, we observe that the values of C_{11}, C_{12}, and C_{44} elastic constants are significantly smaller than the linear interpolated values between the elastic constants of AlN and InN, and the values of C_{33} elastic constant are significantly larger than the corresponding interpolated values. For the alloys with uniform distribution of In atoms, only C_{11} elastic constant deviates significantly from linear dependence on composition.
4
Content available remote

Influence of Chemistry on the Energy Band Structure: AlAs Versus GaAs

100%
Bogusławski P., Gorczyca I.
Acta Physica Polonica A
|
1991
|
vol. 80
|
issue 3
433-436
EN
Energy band structure of AlAs and GaAs is analyzed in terms of the energy structure of the constituent atoms. Conduction band wave functions are projected on s-, p-, and d-symmetry atomic orbitals. The resulting information is combined with the eigenenergies of Al and Ga atoms, in order to-discuss the character of the band gaps, and the sign of deformation potentials.
5
Content available remote

ZnS/ZnSe Superlattices under Pressure

100%
Gorczyca I., Christensen N.
Acta Physica Polonica A
|
1993
|
vol. 84
|
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.
6
Content available remote

Calculations of Point Defects in AlN and GaN; Lattice Relaxation Effects

81%
Gorczyca I., Christensen N. E., Svane A.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 4
785-788
EN
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.
7
Content available remote

Calculations of Native Defects and Impurities in Cubic GaN Including High Pressure Effects

81%
Gorczyca I., Svane A., Christensen Ν. E.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 4
723-726
EN
Using the Green-function matrix technique based on the linear muffin-tin orbital method in the atomic-spheres approximation we perform self-consist­ent calculations of the electronic structure for native defects and impurities in cubic GaN. Native defects as N and Ga vacancies and antisites and substi­tutional impurities: Zn, C and Ge in different charge states are investigated. Resulting positions of the defect levels are compared with tight-binding and pseudopotential calculations. High pressure behavior is also studied in com­parison with some other theoretical and experimental data.
8
Content available remote

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.
9
Content available remote

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
|
2007
|
vol. 112
|
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.
10
Publication available in full text mode
Content available

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.
|
|
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.
11
Content available remote

Band Structure and Refractive Index of Gallium Nitride Under Pressure

62%
Perlin P., Gorczyca I., Suski T., Teisseyre H., Grzegory I., Christensen N.
Acta Physica Polonica A
|
1991
|
vol. 80
|
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.
12
Content available remote

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
|
1992
|
vol. 82
|
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.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.