Ac Conductivity and Dielectric Properties of Amorphous Ge15Se60X25 (X = As or Sn) Films |
| N.A. Hegab, M.A. Afifi, H.E. Atyia and M.I. Ismael
Physics Department, Faculty of Education, Ain Shams University, Cairo, Egypt |
| Received: May 8, 2010; in final form: October 11, 2010 |
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| The ac conductivity and dielectric properties of Ge15Se60 X25 (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 102-105 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 ε1 were found to decrease with frequency and increase with temperature. The maximum barrier height Wm 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. |
| DOI: 10.12693/APhysPolA.119.416 PACS numbers: 72.80.Ng, 77.22.-d |