Origin of multi-level switching and telegraphic noise in organic nanocomposite memory devices

Song, Young-Jae; Jeong, Hyunhak; Chung, Seungjun; Ahn, Geun Ho; Kim, Tae‐Young; Jang, Jingon; Yoo, Daekyoung; Jeong, Hoon; Javey, Ali; Lee, Takhee

doi:10.1038/srep33967

Cited by 24 publications

(27 citation statements)

References 43 publications

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“…It is also obvious that the turn‐on process occurs through discrete events in which the current abruptly changes. The percolation conducting path models may explain the experimental results above. Every step increase in the current may represent a new current path formation.…”

Section: Resultsmentioning

confidence: 80%

“…Various experimental tools have been employed to investigate the fundamental properties of ORRAM devices; for example, impedance spectroscopy to directly probe the charge trapping in the active layer and a direct spatial mapping of the current paths within the layer via elemental analysis . We have recently employed 1/ f noise measurements to show that the conduction paths in organic nanocomposite memory devices form a percolation network from the resistance scaling of the 1/ f noise . A further study of time–dependent current fluctuation behaviors during the turn‐off process in the NDR region demonstrated that the percolating conduction paths dynamically changed before completely getting disconnected (i.e., OFF state) .…”

Section: Introductionmentioning

confidence: 99%

“…We have recently employed 1/ f noise measurements to show that the conduction paths in organic nanocomposite memory devices form a percolation network from the resistance scaling of the 1/ f noise . A further study of time–dependent current fluctuation behaviors during the turn‐off process in the NDR region demonstrated that the percolating conduction paths dynamically changed before completely getting disconnected (i.e., OFF state) . However, there has been little research conducted on the formation process of this percolation network during the turn‐on process.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of Time–Dependent Resistive Switching Behaviors of Unipolar Nonvolatile Organic Memory Devices

Lee

Kim

Song

et al. 2018

Adv Funct Materials

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Organic resistive memory devices are one of the promising next-generation data storage technologies which can potentially enable low-cost printable and flexible memory devices. Despite a substantial development of the field, the mechanism of the resistive switching phenomenon in organic resistive memory devices has not been clearly understood. Here, the time-dependent current behavior of unipolar organic resistive memory devices under a constant voltage stress to investigate the turn-on process is studied. The turn-on process is discovered to occur probabilistically through a series of abrupt increases in the current, each of which can be associated with new conducting paths formation. The measured turn-on time values can be collectively described with the Weibull distribution which reveals the properties of the percolated conducting paths. Both the shape of the network and the current path formation rate are significantly affected by the stress voltage. A general probabilistic nature of the percolated conducting path formation during the turn-on process is demonstrated among unipolar memory devices made of various materials. The results of this study are also highly relevant for practical operations of the resistive memory devices since the guidelines for time-widths and magnitudes of voltage pulses required for writing and reading operation can be potentially set.

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Section: Resultsmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of Time–Dependent Resistive Switching Behaviors of Unipolar Nonvolatile Organic Memory Devices

Lee

Kim

Song

et al. 2018

Adv Funct Materials

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“…Notice that that the Green's functions, self-energies, and their derivatives will become scalars for transport in the single molecular energy level case and therefore the commutator term will vanish. We now consider the equation of motion for the lesser Green's function which is given by (17). The expansions (18) and (19) are substituted into (17) and, as before, split based on order to give…”

Section: B Non-adiabatic Expansion Of Kadanoff-baym Equations In Wigmentioning

confidence: 99%

“…We now consider the equation of motion for the lesser Green's function which is given by (17). The expansions (18) and (19) are substituted into (17) and, as before, split based on order to give…”

Section: B Non-adiabatic Expansion Of Kadanoff-baym Equations In Wigmentioning

confidence: 99%

Current-induced atomic motion, structural instabilities, and negative temperatures on molecule-electrode interfaces in electronic junctions

2020

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Molecule-electrode interfaces in molecular electronic junctions are prone to chemical reactions, structural changes, and localized heating effects caused by electric current. These can be exploited for device functionality or may be degrading processes that limit performance and device lifetime. We develop a nonequilibrium Green's function based transport theory in which the central region atoms and, more importantly, atoms on molecule-electrode interfaces are allowed to move. The separation of time-scales of slow nuclear motion and fast electronic dynamics enables the algebraic solution of the Kadanoff-Baym equations in the Wigner space. As a result, analytical expressions for dynamical corrections to the adiabatically computed Green's functions are produced. These dynamical corrections depend not only on the instantaneous molecular geometry but also on the nuclear velocities. To make the theoretical approach fully self-consistent, the same time-separation approach is used to develop expressions for the adiabatic, dissipative, and stochastic components of current-induced forces in terms of adiabatic Green's functions. Using these current induced forces, the equation of motion for the nuclear degrees of freedom is cast in the form of a Langevin equation. The theory is applied to model molecular electronic junctions. We observe that the interplay between the value of the spring constant for the molecule-electrode chemical bond and electronic coupling strength to the corresponding electrode is critical for the appearance of structural instabilities and, consequently, telegraphic switching in the electric current. The range of model parameters is identified to observe structurally stable molecular junctions as well as various different kinds of current-induced telegraphic switching. The interfacial structural instabilities are also quantified based on current noise calculations.

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Resistive Switching by Percolative Conducting Filaments in Organometal Perovskite Unipolar Memory Devices Analyzed Using Current Noise Spectra

Ahn

Kang

Song

et al. 2021

Adv Funct Materials

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Organometal halide perovskites have emerged as potential material systems for resistive memory devices besides their outstanding optical and electrical properties. Although halide-perovskite resistive memory has the advantage of operating with a low voltage and large on/off ratio, random distribution in operation voltage remains a challenge in memory application. This stochastic operation characteristic is due to the random formation of conducting filaments that cause resistance fluctuations in the material. Therefore, it is essential to investigate the formation and dissolution of conducting filaments and their structure. However, direct observation of a nanoscale filamentary structure is often challenging. Moreover, detailed studies of conducting filaments in halide-perovskite materials have rarely been reported. By employing a scaling theory with a fractal structure, this study investigates the geometric structures and dynamics of conducting filaments formed in organometal halide perovskite through current noise analysis. The temperature-dependent electrical properties and current noise demonstrate the role of ion migration in the formation of conducting filaments. The findings could enhance the understanding of the resistive switching phenomena of perovskite resistive memory devices in terms of percolative conducting filaments. Thus, providing a route for achieving a stable memory operation by controlling the relevant structure and dynamics of the switching processes.

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Origin of multi-level switching and telegraphic noise in organic nanocomposite memory devices

Cited by 24 publications

References 43 publications

Investigation of Time–Dependent Resistive Switching Behaviors of Unipolar Nonvolatile Organic Memory Devices

Investigation of Time–Dependent Resistive Switching Behaviors of Unipolar Nonvolatile Organic Memory Devices

Current-induced atomic motion, structural instabilities, and negative temperatures on molecule-electrode interfaces in electronic junctions

Resistive Switching by Percolative Conducting Filaments in Organometal Perovskite Unipolar Memory Devices Analyzed Using Current Noise Spectra

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