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Wyświetlanie 1-3 z 3
Tytuł:
Pressure-Driven Reordering of Valence Band States in AlGaN/AlN Quantum Wells
Autorzy:
Łepkowski, S.
Bardyszewski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1403639.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
78.67.De
62.50.-p
Opis:
We study theoretically the influence of external hydrostatic pressure on the valence band structure in [0001]-oriented $Al_{x}Ga_{1-x}N$/AlN quantum wells used in deep-ultraviolet light emitting devices. The calculations performed using the multi-band k·p method with excitonic effects show that for $Al_{x}Ga_{1-x}N$/AlN quantum wells with x = 0.7 and quantum well width of 1.5 nm, reordering of the topmost valence subbands having different symmetries occurs with increasing pressure. In these structures, at low pressure values the topmost valence level is of $\Gamma p_9$ symmetry whereas it changes to the $\Gamma p_7$ state for pressures about 2.5 GPa. We also find that the excitonic effects increase the critical value of pressure at which the change in the polarization of the emitted light occurs to 7 GPa. This behavior is opposite to the pressure-dependent reordering of the topmost valence band states in thin GaN/AlGaN quantum wells which occurs from $\Gamma p_7$ to $\Gamma p_9$ states.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1029-1030
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pressure Dependence of the Light Emission in Zinc-Blende InGaAs/GaAs and InGaN/GaN Quantum Wells
Autorzy:
Łepkowski, S.
Gorczyca, I.
Powiązania:
https://bibliotekanauki.pl/articles/1791301.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.D-
62.50.-p
81.40.Jj
78.67.De
Opis:
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.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 857-858
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Nonlinear Elasticity and Electromechanical Coupling on Optical Properties of InGaN/GaN and AlGaN/AlN Quantum Wells
Autorzy:
Łepkowski, S. P.
Majewski, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/2046928.pdf
Data publikacji:
2006-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.De
62.20.Dc
77.65.-j
Opis:
We present theoretical studies of effects of the nonlinear elasticity and the electromechanical coupling on the optical properties of InGaN/GaN and AlGaN/AlN quantum wells. In these structures, due to the lattice misfit between constituents, the quantum wells are compressively strained and the intrinsic hydrostatic pressure is present. Therefore, the nonlinear elasticity is investigated by taking into account the pressure dependence of elastic stiffness tensor for the strained quantum wells. We show that this effect leads to (i) decrease in the volumetric strain and (ii) increase in the polarization-induced built-in electric field in the quantum wells. Consequently, the interband transition energies in the quantum wells decrease when the nonlinear elasticity of nitrides is considered. On the other hand, we show that the effect of electromechanical coupling, i.e., co-existence of ordinary and converse piezoelectric effects results in increase in the interband transition energies in the considered quantum wells. It turns out that the influence of the nonlinear elasticity on the optical properties is stronger than the influence of electromechanical coupling for InGaN/GaN quantum wells, while for AlGaN/GaN the opposite situation is observed.
Źródło:
Acta Physica Polonica A; 2006, 110, 2; 237-242
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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