Ac conductivity and dielectric properties of Ga2S3–Ga2Se3 films (original) (raw)
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Se "lms of di!erent thicknesses were prepared by thermal evaporation technique. X-ray di!raction measurements showed that the as-deposited In Se "lms and those annealed at 373, 423, and 473 K are in the amorphous state. The composition of the investigated "lms is checked using energy dispersive X-ray spectroscopy (EDX) technique. The ac conductivity and dielectric properties of the amorphous In Se "lms have been investigated in the frequency range 100 Hz}100 kHz. The ac conductivity ( ) is found to be proportional to Q where s(1. The temperature dependence of both ac conductivity and the parameter s is reasonably well interpreted by the correlated barrier hopping (CBH) model. Values of dielectric constant and dielectric loss were found to decrease with frequency and increase with temperature. The maximum barrier height W + calculated from dielectric measurements according to Guintini equation agrees with that proposed by the theory of hopping of charge carriers over potential barrier as suggested by Elliot in case of chalcogenide glasses. The e!ect of annealing at di!erent temperatures on the ac conductivity and dielectric properties is also investigated. Values of ( ), and were found to increase with higher annealing temperature due to the increase of the degree of ordering of the investigated "lms.
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The electric conductivity of chalcogenide glassy semiconductor xAg 2 S-(1-x)(0.5S-0.5Te) has been presented here as a function of temperature and frequency. Formation of different nanocrystallites has been confirmed from X-ray diffraction study. It is also noteworthy that average size of nanocrystallites decreases with the increase of dislocation density. Dc conductivity data have been interpreted using Mott's model and Greaves's model in low and high temperature regions respectively. Ac conductivity above the room temperature has been analysed using Meyer-Neldel (MN) conduction rule. It is interestingly noted that Correlated Barrier Hopping (CBH) model is the most appropriate conduction mechanism for x = 0.35, where pairs of charge carrier are considered to hop over the potential barrier between the sites via thermal activation. To interpret experimental data for x = 0.45, modified non-overlapping small polaron tunnelling (NSPT) model is supposed to be appropriate model due to tunnelling through grain boundary. The conductivity spectra at various temperatures have been analyzed using Almond-West Formalism (power law model). Scaling of conductivity spectra reveals that electrical relaxation process of charge carriers (polaron) is temperature independent but depends upon the composition of the present chalcogenide glassy system.
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Journal of Non-Crystalline Solids, 1998
The Ag 2 S±Ga 2 S 3 ±GeS 2 pseudo ternary system shows a large glass-forming region. Ternary glass formation does not reach the Ga 2 S 3 ±Ag 2 S binary system. Electrical properties of the glasses were investigated by measuring complex impedance. For instance, at 298 K, for the xAg 2 S±Ga 2 S 3 ±(9 A x)GeS 2 compositions (x 1±6) electrical conductivity and activation energy vary roughly between 10 À10 and 10 À5 S cm À1 , and 0.60 and 0.34 eV, respectively. Ionic transference number measurements and electronic transference number estimates indicate that these glasses are essentially ionic conductors.
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The structural features and morphology of investigated Sb2S3 powder were analyzed by X-ray diffraction and scanning electron microscope techniques. The dependence of dielectric properties and ac conductivity of bulk Sb2S3 as pellet on both of frequency (102–106 Hz) and temperature (303-393 K) were studied. The dielectric constant (121.2-45.8) and dielectric loss (53.3-0.89) displayed noticeable dependence on frequency and in the investigated range of temperature 303-393 K. The frequency dependence of ac conductivity σac(ω) follows up the power relation; σac(ω) = Gωs. The frequency exponent s, diminished with the rise in temperature, implying that the correlated barrier hopping (CBH) is the predominant conduction mechanism. The ac conductivity exhibited a thermally activated nature. The localized states N(EF) values recorded in order of 1018 eV-1.cm-3 at specific temperatures for frequency of 800 Hz. Activation energy ΔE, calculated at different frequencies indicating a decrease from...
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Ge weight doping percentage by 1% antimony (Ge:Sb) films have been deposited by thermal evaporation technique on glass substrate at room temperature under vacuum of 10-5 mbar with rate of deposition near to 10Å/sec. These films of different thickness (0.25, 0.5, 0.75, 1.0) µm have been annealed at different temperatures Ta (373, 473)K, to study the effect of thickness and annealing temperature on the electrical properties. These properties include the (DC, AC) conductivity from which the transport mechanism of the charge carriers can be estimated, and also the Hall Effect which gives information about the type, density and mobility of carriers.
EFFECT OF Cd ADDITION ON THE AC CONDUCTIVITY AND DIELECTRIC PROPERTIES OF Ge70Te30 FILMS
Se 70 Te 30 and Se 70 Te 20 Cd 10 films of different thicknesses were prepared by thermal evaporation technique. X-ray diffraction patterns analysis showed that the films were in the amorphous state. The ac conductivity and dielectric properties of the obtained films in the frequency range (10 2 -10 5 Hz) has been investigated. The ac conductivity is found to be proportional to ω s where s<1. The temperature dependence of both the ac conductivity and the parameter s is reasonably interpreted by the correlated barrier hopping CBH model. The maximum barrier height W M ,for each composition calculated from dielectric measurements according to Guintini equation, agrees with that proposed by the theory of hopping of charge carriers over potential barrier as suggested by Elliott in case of chalcogenide glasses.
Physica Status Solidi A-applications and Materials Science - PHYS STATUS SOLIDI A-APPL MAT, 2010
Ga 2 Te 3 crystallizes in the zinc-blende structure where one-third of the cation sites are vacant. The dielectric properties of asgrown Ga 2 Te 3 crystals have been studied in the frequency range from 10 2 to 10 9 Hz. Below room temperature, the dielectric constant is around 20 and almost independent of temperature. The ac conductivity is found to obey a power law s ac $ v s , with s $ 1 indicating that the conduction is due to hopping of localized charge carriers. Above room temperature the dielectric constant shows an S-shaped step-like increase up to a very large value around 10 4. The relaxation is found to be of thermal activated Debye type, the relaxation time changes as t ¼ t 0 expðE t =kTÞ (E t % 0:27 eV). The activation energy of the relaxation nearly coincides with that deduced from conductivity. These results are analyzed using the Maxwell Wagner model and the space charge model.