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Wyszukujesz frazę "Afifi, M." wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
Ac Conductivity and Dielectric Properties of Amorphous $Ge_{15}Se_{60}X_{25}$ ( X = As or Sn) Films
Autorzy:
Hegab, N.
Afifi, M.
Atyia, H.
Ismael, M.
Powiązania:
https://bibliotekanauki.pl/articles/1505386.pdf
Data publikacji:
2011-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ng
77.22.-d
Opis:
The ac conductivity and dielectric properties of $Ge_{15}Se_{60} X_{25}$ (X = As or Sn) thin films are reported in this paper. The thin films were deposited by thermal evaporation at $10^{-5}$ Torr pressure. The films were well characterized by X-ray diffraction, differential thermal analysis and energy dispersive X-ray spectroscopy. The ac conductivity was measured over temperature range 303-413 K and frequency range $10^2-10^5$ Hz. The frequency dependence of the ac conductivity was found to be linear with slope which lies very close to unity and is independent of temperature. This behavior can be explained in terms of the correlated barrier hopping between centers forming intimate valence alternation pairs. Values of the dielectric constant $ε_1$ were found to decrease with frequency and increase with temperature. The maximum barrier height $W_{m}$ for each sample, which was calculated from the dielectric measurements according to the Guinitin equation, agrees with the theory of hopping of charge carriers over potential barrier as suggested by Elliott in case of chalcogenide glasses. The density of localized state near the Fermi level was estimated for the studied films.
Źródło:
Acta Physica Polonica A; 2011, 119, 3; 416-423
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrical and Dielectric Properties of Amorphous Ge$\text{}_{1}$Se$\text{}_{1.35}$TL$\text{}_{0.1}$ Films
Autorzy:
Abdel-Aziz, M. M.
Afifi, M. A.
Labib, H. H.
El-Metwally, E. G.
Powiązania:
https://bibliotekanauki.pl/articles/2014346.pdf
Data publikacji:
2000-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ng
72.20.-i
Opis:
The temperature dependence of the DC and AC electrical conductivity were measured for Ge$\text{}_{1}$Se$\text{}_{1.35}$Tl$\text{}_{0.1}$ films. The value of DC electrical conduction energy ΔE$\text{}_{σ}$ does not depend on film thickness in the investigated range with mean value of 0.72eV. The AC conductivity σ$\text{}_{AC}$ is related to frequency by the expression σ$\text{}_{AC}$=Aω$\text{}^{S}$, where S is the frequency exponent which decreases linearly with increasing temperature. This can be explained in terms of the pair (bipolaron) correlated barrier hopping model suggested by Elliott. The frequency and temperature dependence of real and imaginary parts of the dielectric constant were studied for Ge$\text{}_{1}$Se$\text{}_{1.35}$Tl$\text{}_{0.1}$ films. The dielectric constant (real part) and the dielectric loss (imaginary part) increase with increasing temperature and decrease with increasing frequency in the investigated range of frequency and temperature. The maximum barrier height W$\text{}_{M}$ can be calculated according to the Giuntini equation at different temperatures. The obtained value of W$\text{}_{M}$ is in good agreement with the theory of hopping of charge carriers over a potential barrier as suggested by Elliott in case of chalcogenide glasses.
Źródło:
Acta Physica Polonica A; 2000, 98, 4; 393-399
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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