A study of phase transition behaviors of chalcogenide layers using <i>in situ</i> alternative-current impedance spectroscopy

Huang, Yun; Huang, Yu-Jen; Hsieh, Tsung−Eong

doi:10.1063/1.4729528

Cited by 11 publications

(13 citation statements)

References 37 publications

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“…The finding of the Nyquist diagram displaying only one semicircle is in striking contrast to literature data, where two semicircles are observed and consequently models comprised of two RC elements are invoked to interpret the data [31,37]. The additional RC element is typically attributed to highly resistive contacts [44] or to highly resistive grain boundaries [31,45,46], where the latter, of course, only makes sense in crystalline systems. As the explanations for the additional RC element are somewhat awkward, it is comforting that our data reveal just one RC element.…”

Section: B Frequency-dependent Permittivity and Conductivitycontrasting

confidence: 67%

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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Section: B Frequency-dependent Permittivity and Conductivitycontrasting

confidence: 67%

Dielectric properties of amorphous phase-change materials

et al. 2017

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“…IS is a powerful tool to study the electrical characteristics of various materials and is already utilized to investigate the conduction behaviors of polycrystalline chalcogenides. [38][39][40][41][42] The Cole-Cole plots and the equivalent circuit used to fit the data are shown in Fig. 3(a).…”

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confidence: 99%

“…The high-and low-frequency regions are attributable to the grains and grain boundaries, respectively. [38][39][40][41][42][43] The grain boundary traps typically have longer relaxation lifetimes (s ¼ RC), because grains are more ordered. The impedance spectra as a function of bias are shown in Fig.…”

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confidence: 99%

Intrinsic memristance mechanism of crystalline stoichiometric Ge2Sb2Te5

Zhong

Zhang

et al. 2013

Applied Physics Letters

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“…The network is floppy below <r>=2.4 and rigid above <r> = 2.4. A later modification of this model [20] based on the formation of two dimensional layer structures and medium range interactions suggests a topological threshold at <r>= 2.67 where a change from two dimensional layered structure to three dimensional network takes place due to cross-linking. The applicability of the ideas of rigidity percolation was verified in many binary and ternary glasses [21][22].…”

Section: IImentioning

confidence: 99%

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Abstract-The composition dependence of energetic parameter (A) in two sets of namely,10,15,20) and 5,10,15,20)

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confidence: 99%