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Wyszukujesz frazę "Lavallard, P." wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
Light Emission by Semiconductor Nanostructures in Dielectric Medium or Close to Plane Interface
Autorzy:
Lavallard, P.
Powiązania:
https://bibliotekanauki.pl/articles/1946709.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Bh
78.55.Cr
78.55.Et
Opis:
We review several situations in which the emission rate of a nanostructure is modified by its environment. We first consider small objects embedded in media with different refractive indices. The local electromagnetic field and the rate of spontaneous emission of the nanostructure are enhanced or inhibited by the induced dipole charges on the interface. In quantum wells or nanocrystals embedded in a low dielectric constant medium, the binding energy of excitons is increased. In anisotropic microcrystals, the local field is anisotropic and emission of light is polarized. We consider especially the case of p$\text{}^{+}$-doped porous silicon in which nanocrystals are elongated. Another interesting situation occurs when a dipole is in the vicinity of a dielectric interface. The local field acting on the dipole results from the interferences of incident and reflected beams. Contributions from evanescent waves are important when the dipole is located in the medium of low refractive index, very close to the surface. The intensity of emission and its pattern are modified by the vicinity of the dielectric interface. Close to the interface semiconductor/air, the exciton binding energy is increased. In the vicinity of a metallic surface, a nonradiative transfer to the metal occurs for small distances of the nano-object or quantum well to the surface and the quantum efficiency varies with the distance to the metallic surface. The exciton binding energy of a quantum well is decreased close to a metallic surface.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 645-666
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Periodic Behavior of the Exciton Oscillator Strength with AlAs Thickness in Type II GaAs AlAs Heterostructures
Autorzy:
Gourdon, C.
Martins, D.
Lavallard, P.
Ivchenko, E. L.
Powiązania:
https://bibliotekanauki.pl/articles/2028741.pdf
Data publikacji:
2001-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.-w
71.70.-d
Opis:
For a single GaAs/AlAs/GaAs type II pseudodirect double quantum well, as well as for superlattices it was predicted that the oscillator strength of the lowest optical transition has a periodic dependence on the number of AlAs monolayers. The oscillator strength depends on the coupling between theΓ and X electron states. We use samples containing a single GaAs/AlAs/GaAs double quantum well with thickness gradient to show experimental evidence of this effect. The results concerning theΓ-X coupling are obtained from the study of the ratio of photoluminescence intensities of the zero-phonon line and the phonon replica and from their time decay. They show the monolayer dependence of the Γ-X mixing potential. We extend the model describing the Γ-X coupling for ideal interfaces in the frame of the envelope approximation to the case of non-abrupt interfaces and exciton localization. The amplitude of variation of the radiative recombination time due to the Γ-X mixing is well reproduced within this model.
Źródło:
Acta Physica Polonica A; 2001, 100, 3; 409-416
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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