AC conductivity and dielectric properties of Sb2Te3 thin films

Te42As36Ge10Si12 chalcogenide composition was prepared by conventional melt-quenching. The ac conductivity and the dielectric properties were carried out in the frequency range 0.5 × 10 3 -4 × 10 6 Hz and temperature range 300-423 K. The analysis of the experimental results of the frequency dependence of ac conductivity σac (ω) indicates that σac(ω) is proportional to ω s where s > 1. The temperature dependence of both ac conductivity and the parameter s is reasonably well interpreted by the correlated barrier hopping model. The maximum barrier height Wm calculated from ac conductivity and the density of localized states were determined. Values of dielectric constant ε1 and dielectric loss ε2 were found to decrease with frequency and increase with temperature. The analysis of dielectric loss leads to determine the barrier height Wm and agrees with that proposed by the theory of hopping of charge carriers over potential barrier between charged defect states as suggested by Elliott in case of chalcogenide glasses.

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“…This behavior of ac conductivity is in agreement with the results obtained before for other amorphous materials [22][23][24]. …”

Section: Ac Conductivitysupporting

confidence: 92%

AC Conductivity and Dielectric Properties οf Amorphous Te₄₂As₃₆Ge₁₀Si₁₂Glass

Hegab

El-Mallah

2009

Acta Phys. Pol. A

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“…The absence of a frequency dependence is by no means trivial, since this finding differs from literature on other chalcogenides such as As 2 Te 3 [47]. If a frequency-dependent conductivity (often of the type σ ∝ ω s ) is observed, this phenomenon is usually attributed to hopping transport [48]. The "flat" conductivity spectra we obtained are perfectly in line with charge transport in extended states at the mobility edge ("band transport").…”

Section: B Frequency-dependent Permittivity and Conductivitycontrasting

confidence: 49%

“…This result is again not trivial. Literature data on other amorphous materials frequently display changes in the permittivity with frequency, which are then explained in terms of dielectric relaxations [48]. Table I and Fig.…”

Section: B Frequency-dependent Permittivity and Conductivitymentioning

confidence: 99%

Dielectric properties of amorphous phase-change materials

et al. 2017

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The dielectric function of several amorphous phase-change materials has been determined by employing a combination of impedance spectroscopy (9 kHz-3 GHz) and optical spectroscopy from the far-(20 cm −1 , 0.6 THz) to the near-(12 000 cm −1 , 360 THz) infrared, i.e., from the DC limit to the first interband transition. While phase-change materials undergo a change from covalent bonding to resonant bonding on crystallization, the amorphous and crystalline phases of ordinary chalcogenide semiconductors are both governed by virtually the same covalent bonds. Here, we study the dielectric properties of amorphous phase-change materials on the pseudobinary line between GeTe and Sb 2 Te 3 . These data provide important insights into the charge transport and the nature of bonding in amorphous phase-change materials. No frequency dependence of permittivity and conductivity is discernible in the impedance spectroscopy measurements. Consequently, there are no dielectric relaxations. The frequency-independent conductivity is in line with charge transport via extended states. The static dielectric constant significantly exceeds the optical dielectric constant. This observation is corroborated by transmittance measurements in the far infrared, which show optical phonons. From the intensity of these phonon modes, a large Born effective charge is derived. Nevertheless, it is known that crystalline phase-change materials such as GeTe possess even significantly larger Born effective charges. Crystallization is hence accompanied by a huge increase in the Born effective charge, which reveals a significant change of bonding upon crystallization. In addition, a clear stoichiometry trend in the static dielectric constant along the pseudobinary line between GeTe and Sb 2 Te 3 has been identified.

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“…The temperature dependent parameter s for the investigated samples is shown in inset gure; it is clear that s decreases with increase of temperature. These results are in agreement with the correlated barrier hopping (CBH) [1921] model, such behaviors were also reported by various researchers [22,23]. According to this model, as suggested by Guintini et al [24] the conduction occurs via bipolaron hopping process where two electrons simultaneously hop over the potential barrier between two defect charge states (D + and D) to form a dipole with relaxation energy, and the barrier height is correlated with interstice separation via a Coulombic interaction.…”

Section: Frequency Dependence Of Ac Conductivitysupporting

confidence: 89%

Ac Conductivity Measurement of Cd₅Se_95-xZn_xChalcogenide Semiconductor Using Correlated Barrier Hopping Model

Ganaie

Zulfequar

2015

Acta Phys. Pol. A

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Cd5Se95−xZnx (x = 0, 2, 4, 6) chalcogenide semiconductors were prepared by conventional melt-quenching and were characterized by X-ray diraction, scanning electron microscopy, and Fourier transform infrared studies. Ac conductivity of Cd5Se95−xZnx chalcogenide semiconductor has been investigated in the frequency range of 1 kHz1 MHz and in the temperature range of 290370 K. The analysis of the experimental results indicates that the ac conductivity is temperature, frequency and concentration dependent. Ac conductivity is found to obey the power law ω s where s < 1. A strong dependence of ac conductivity and exponent s can be well interpreted in terms of correlated barrier hopping model. The maximum barrier height Wm were calculated from the results of dielectric loss according to the Guintini equation that agree with the theory of hopping of charge carriers over potential barrier as suggested by Elliot in case of chalcogenide semiconductors.

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AC conductivity and dielectric properties of Sb2Te3 thin films

Cited by 81 publications

References 27 publications

AC Conductivity and Dielectric Properties οf Amorphous Te₄₂As₃₆Ge₁₀Si₁₂Glass

AC Conductivity and Dielectric Properties οf Amorphous Te₄₂As₃₆Ge₁₀Si₁₂Glass

Dielectric properties of amorphous phase-change materials

Ac Conductivity Measurement of Cd₅Se_95-xZn_xChalcogenide Semiconductor Using Correlated Barrier Hopping Model

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AC conductivity and dielectric properties of Sb2Te3 thin films

Cited by 81 publications

References 27 publications

AC Conductivity and Dielectric Properties οf Amorphous Te42As36Ge10Si12Glass

AC Conductivity and Dielectric Properties οf Amorphous Te42As36Ge10Si12Glass

Dielectric properties of amorphous phase-change materials

Ac Conductivity Measurement of Cd5Se95-xZnxChalcogenide Semiconductor Using Correlated Barrier Hopping Model

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AC Conductivity and Dielectric Properties οf Amorphous Te₄₂As₃₆Ge₁₀Si₁₂Glass

AC Conductivity and Dielectric Properties οf Amorphous Te₄₂As₃₆Ge₁₀Si₁₂Glass

Ac Conductivity Measurement of Cd₅Se_95-xZn_xChalcogenide Semiconductor Using Correlated Barrier Hopping Model