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1

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

100%

Gorczyca I., Christensen N. E., Svane A.

Acta Physica Polonica A

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1997

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vol. 92

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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.

2

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

100%

Gorczyca I., Svane A., Christensen Ν. E.

Acta Physica Polonica A

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1995

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vol. 88

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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.

3

Calculations of Native Defects in Cubic AlN

100%

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.

4

Electronic Band Structure of In_xGa_{1-x}N under Pressure

88%

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.

5

Electronic Structure and Optical Properties of GaAs_{1-x}N_x and Ga_{1-x}B_xAs Alloys

88%

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.

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

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

Calculations of Native Defects in Cubic AlN

Electronic Band Structure of In_xGa_{1-x}N under Pressure

Electronic Structure and Optical Properties of GaAs_{1-x}N_x and Ga_{1-x}B_xAs Alloys