Electrical Conduction Mechanisms and Dielectric Constants of Nanostructure Zinc Indium Selenide Thin Films

Document Type : Original articles

Authors

1 Department of physics, Faculty of science,34517, University of Damietta. Egypt

2 Department of physics, faculty of science at New Damietta, 34517, university of Damietta. Egypt

3 Department of physics, Faculty of science, Al-Jabl Al-Gharbi University, Libya

Abstract

ZnIn2Se4 has polycrystalline structure in as synthesized powder form; it becomes nanocrystallites
upon thermal deposition. The crystallite size increases by increasing annealing temperature. The
radial distribution function showed that in the first short range order shell; Se atom is tetrahedral
surrounded by a vacancy and three cationic sites occupied by the metal atoms in the ratio 2/3 of In
and 1/3 of Zn. The medium range order region is attributed to In-In pairs having a layered
structure of connected distorted octahedral. The direct current density–voltage characteristics for
Au / ZnIn2Se4 / Au of planar structure revealed three conduction mechanisms depending on
applied potential; namely they are consequently generation- recombination, Ohmic and
exponential trap space charge limited conduction mechanisms. The AC electrical conductivity and
dielectric relaxation of ZnIn2Se4 thin films in the temperature range 305–493 K and in frequency
range 1 kHz –4M Hz has also been studied. Analysis of lnac- ln ω curves showed that band-type
conduction process occurs in frequency range < 1945 Hz. For frequencies > 1945 Hz, ac increases
linearly with the increase in frequency and this is associated with hopping type conduction
mechanism. Analysis of these results proved that conduction occurs by phonon assisted hopping
between localized states and it is performed by bipolaron hopping mechanism. The temperature
and frequency dependence of both the real and imaginary parts of the dielectric constant have been
investigated..

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