Intrinsic memristance mechanism of crystalline stoichiometric Ge2Sb2Te5

Li, Y.; Zhong, Yingpeng; Zhang, J. J.; Xu, Xiangxiang; Wang, Q.; Xu, Lei; Sun, Huajun; Miao, Xiang

doi:10.1063/1.4816283

Cited by 34 publications

(22 citation statements)

References 46 publications

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“…(4), indicate that the very simple model already offers a very accurate description of the data. 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.…”

Section: B Frequency-dependent Permittivity and Conductivitycontrasting

confidence: 66%

“…Prokhorov et al [31] and Li et al [37] reported that the resistivity of Ge 2 Sb 2 Te 5 decreases by merely 1 order of magnitude on crystallization. This observation is in conflict with the majority of studies agreeing on a resistivity decrease of about 3-4 orders of magnitude [9,38] when crystallizing PCMs.…”

Section: Published By the American Physical Society Under The Terms Omentioning

confidence: 99%

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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: 66%

Section: Published By the American Physical Society Under The Terms Omentioning

confidence: 99%

Dielectric properties of amorphous phase-change materials

et al. 2017

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“…Chua circuit with two diodes and resistors implementing non-linear resistor behavior [8] In order to implement new modified Chua's circuit with GST memristor, the GST memristor's emulator circuit with arXiv:1805.06622v2 [eess.SP] 19 May 2018 3 different levels resistors and two capacitors was constructed because there is no already designed model of GST memristor. As it was suggested by Li et al [9], the emulator circuit consisting of contact resistor of the electrodes R s serially connected to parallel connection of pure resistor and capacitor of GST (R p and C p ). In order to better represent equivalent behavior of the GST memristor two main sources of defect in crystalline grain and at grain boundaries should be considered.…”

Section: Gst Memristor Emulator Circuitmentioning

confidence: 99%

Notice of Retraction: Implementation of True Random Number Generator based on Double-Scroll Attractor circuit with GST memristor emulator

Abzhanova

Dolzhikova

James

2018

2018 International Conference on Computing and Network Communications (CoCoNet)

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The cryptographic security provided by various techniques of random number generator (RNG) construction is one of the developing researches areas today. Among various types of RNG, the true random bit generator (TRBG) can be considered as the most unpredictable and most secured because its randomness seed is generated from chaotic sources. This paper proposes a design of TRBG model based on double-scroll attractors circuits with GST memristor. After implementation and simulation of the chaotic circuit with GST memristor emulator, the chaotic behavior of the output voltage and inductor current were received. Moreover, their dependence on the input voltage revealed the close to double-scroll form. The randomness generated from the proposed circuit was tested by receiving Fast Fourier Transform (FFT) and Lyapunov exponents of the output voltage.

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“…Resistive random access memory (RRAM), which achieves data storage through reversible resistance changes in certain dielectrics, is one of the leading candidates for this purpose. Reproducible resistive switching phenomena have been widely observed in oxides [6][7][8][9], chalcogenides [10] and even organic materials [11]. Due to their simple device structure (metal/insulator/metal), high compatibility to standard CMOS flow line and the prospect of 3D integration, certain binary oxides such as Al 2 O 3 [12], HfO 2 [13,14], TiO2 [15,16], and ZrO 2 [17] have attracted more attention.…”

Section: Introductionmentioning

confidence: 99%

GGA-1/2 self-energy correction for accurate band structure calculations: the case of resistive switching oxides

et al. 2018

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First-principles calculation has become an indispensable methodology in revealing the working principles of nanoscale electronic devices, but ultra-large supercells are usually required in modeling the devices with critical metal/dielectric interfaces. Traditional density functional theory within the generalized gradient approximation (GGA) suffers from the inaccurate band gap problem when metal oxides are present, but they serve as the core component in resistive random access memory (RRAM), which is a promising path for novel high speed non-volatile memories. To obtain improved oxide band gaps, we applied the efficient GGA-1/2 method for self-energy correction, whose computational load is at the same level as standard GGA. In particular, we have investigated the influence of exchange-correlation functional flavors on the GGA-1/2 band structures, taking four important binary oxide RRAM materials (α-Al 2 O 3 , r-TiO 2 , m-ZrO 2 and m-HfO 2 ) as benchmark examples. Five GGA functionals (PBE, PBEsol, PW91, revPBE and AM05) were considered and their band structures were compared in detail. We have found that the performance of GGA-1/2 is comparable to state-ofthe-art GW and generally superior to the HSE06 hybrid functional. Among the five GGA functionals, PBEsol yields the best results in general. In addition, the applicability of a single self-energy potential for various GGA-1/2 flavors is discussed. Our work provides a guide to the GGA flavor selection, when applying the GGA-1/2 method to metal oxides. manifest a transition from a high resistance state (HRS) to a low resistance state (LRS) upon the formation of conductive filaments (CFs) connecting the two electrodes. Yet, at present there are still controversies on the exact composition and geometry of the CFs [19][20][21][22]. Since it is difficult to directly observe and determine experimentally the exact composition of the CFs within the dielectric media, theoretical approaches can be particularly helpful.Among atomistic simulation techniques, ab initio calculations based on density functional theory (DFT) [23] are highly successful in the prediction of total energies, bond lengths, and vibration frequencies. However, DFT within local density approximation (LDA) or generalized gradient approximation (GGA) severely underestimates the band gaps of semiconductors and insulators, which limits its capability of predicting the band alignment in metal/semiconductor contacts, a significant task in understanding charge transmission through CFs [24]. Various theoretical approaches have been proposed to overcome this shortcoming, thus providing more reliable predictions of physical properties that depend on excited states. Hedin's GW approximation is considered to be the state-of-the-art, which is still the most accurate method for electronic structure calculation. It calculates the quasiparticle energies in terms of the perturbation theory [25], and is a beyond-DFT technique. Hybrid functionals [26], which combine standard DFT and Hartree-Fock exchange functionals thro...

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Intrinsic memristance mechanism of crystalline stoichiometric Ge2Sb2Te5

Abstract: Articles you may be interested inDirect imaging of crystal structure and defects in metastable Ge2Sb2Te5 by quantitative aberration-corrected scanning transmission electron microscopy Appl. Phys. Lett.

Cited by 34 publications

References 46 publications

Dielectric properties of amorphous phase-change materials

Dielectric properties of amorphous phase-change materials

Notice of Retraction: Implementation of True Random Number Generator based on Double-Scroll Attractor circuit with GST memristor emulator

GGA-1/2 self-energy correction for accurate band structure calculations: the case of resistive switching oxides

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