Interpretation of nanoscale conducting paths and their control in nickel oxide (NiO) thin films

Yoo, In-Kyeong; Kang, Bo-Kyeong; Park, Y. D.; Lee, Myoung-Jae; Park, Y.

doi:10.1063/1.2936087

Cited by 38 publications

(24 citation statements)

References 13 publications

(10 reference statements)

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“…I T has been demonstrated that the resistive switching in NiO thin films is controlled by electrical power and subject to Poisson distribution when electrical power consumed during switching is properly quantified [1]. The electrical power consumption values were quantified by grouping them with proper range, so that the data may be fitted to Poisson distribution with the normalized electrical power values of natural number m, as reported in [1].…”

Section: Introductionmentioning

confidence: 99%

“…The electrical power consumption values were quantified by grouping them with proper range, so that the data may be fitted to Poisson distribution with the normalized electrical power values of natural number m, as reported in [1]. It was proposed in [1] that m may be equal to number of filaments either formed or ruptured during resistance switching based on the filamentary switching mechanism [1]. The number, however, has broad range and detailed study is required to understand how the quantified switching power values are related to filaments.…”

Section: Introductionmentioning

confidence: 99%

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Fractal Dimension of Conducting Paths in Nickel Oxide (NiO) Thin Films During Resistance Switching

Yoo

Kang

Ahn

et al. 2010

IEEE Trans. Nanotechnology

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A resistance-switching model in nickel oxide thin film is proposed based on Poisson distribution of electrical switching power. Conductive percolating network in soft breakdown surface may be the source of resistance switching. The main body of network may remain unchanged, but a portion of network is broken and healed repeatedly during switching. Dependence of reset current on electrode area is explained by fractal dimension.Index Terms-Nickel oxide, resistance switching, soft breakdown, switching power.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fractal Dimension of Conducting Paths in Nickel Oxide (NiO) Thin Films During Resistance Switching

Yoo

Kang

Ahn

et al. 2010

IEEE Trans. Nanotechnology

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“…Therefore, the temperature distribution is another key factor governing the switching behavior. 10 Considering the different types of electrical carriers in TiO 2 ͑electron͒ and NiO ͑hole͒, local rupture and recovery can occur in a region near the cathode interface in a metal/NiO/metal. Under the given bias condition, O 2− ions move to the anode ͑or even to the atmosphere͒, which results in an oxygen-deficient TiO 2−x in TiO 2 and nickel-excess Ni 1+x O in NiO.…”

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confidence: 99%

Filamentary Resistive Switching Localized at Cathode Interface in NiO Thin Films

Kim

Choi

Song

et al. 2009

J. Electrochem. Soc.

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This study examined the resistance switching mechanism of the W tip/40 nm NiO/Ir and Pt/40 nm NiO/Ir structures in a voltage sweep mode. The results showed that the conducting filaments propagate from the anode interface, and resistance switching is induced by the rupture and recovery of the conducting filaments in the localized regions near the cathode. This is in contrast to what is observed in TiO 2 ͓Kim et al., Appl. Phys. Lett., 91, 012907 ͑2007͔͒, where the filamentary switching occurs at the anode interface. NiO is a p-type electrical conduction material. Localized hole injection at the anode interface induced the removal of oxygen ions from NiO to the anode ͑or atmosphere͒ by the Joule heating-assisted electromigration. This eventually leads to the metallic Ni filament formation extending from the anode interface to the cathode interface. The weaker Ni filament near the cathode interface induced a larger local heat generation for the given switching currents, which leads to the cathode interface localized switching.Reliable resistance switching has been reported in many metal oxide systems and may have potential applications in future nonvolatile semiconductor memory devices. Among the range of resistance switching metal/binary oxide/metal systems, NiO and TiO 2 are perhaps the most widely studied resistance-switching materials, 1-5 where the electrode material is typically a noble metal. Resistance switching in these systems has been reported to be closely related to the formation and rupture of conducting filaments. 1-5 It is reasonable to assume that the filaments are formed by the percolation of defects, such as oxygen vacancies ͑V O ͒ in TiO 2 and Ni interstitial ions ͑Ni i ͒ in NiO, which may contribute to electrical conduction. 6,7 It was recently reported that the rupture and recovery of filaments, corresponding to the RESET ͓switching from the low resistance state ͑LRS͒ to high resistance state ͑HRS͔͒ and SET switching ͑switching from the HRS to LRS͒, respectively, in a 40 nm thick TiO 2 film occur in a localized region ͑3-10 nm thick͒ near the anode interface in a unipolar resistive switching mode through the unidirectional electromigration of oxygen ions. 8 The current flow through these tiny filaments heats the filament area to high temperatures ͑a few hundred degrees͒, 9 which means that the electromigration of defects is thermally assisted. Therefore, the temperature distribution is another key factor governing the switching behavior. 10 Considering the different types of electrical carriers in TiO 2 ͑electron͒ and NiO ͑hole͒, local rupture and recovery can occur in a region near the cathode interface in a metal/NiO/metal. Under the given bias condition, O 2− ions move to the anode ͑or even to the atmosphere͒, which results in an oxygen-deficient TiO 2−x in TiO 2 and nickel-excess Ni 1+x O in NiO. As the electromigration of O 2− ions in both materials is a thermally activated process, achieving a local high temperature, due to the electrical carrier injection at a localized point at the elec...

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“…Filament formation, accompanied by oxygen ion movement in most cases, is a very disordered process. [4][5][6] This results in the fluctuations of various switching parameters, such as the switching voltage and on and off currents. The other reason originated from the distortion of the stimulus signal for initiating RS.…”

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confidence: 99%

Methods of Set Switching for Improving the Uniformity of Filament Formation in the TiO[sub 2] Thin Film

Kim

Song

Kim

et al. 2010

Electrochem. Solid-State Lett.

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The parameters determining the set state current and reset voltage, determined by the strength of formed filaments, were examined using current pulse and voltage driven current-voltage ͑I-V͒ sweeps. In the pulse switching measurement, the total current flow, including overshooting noise effect at the moment of set switching, was found to determine the strength of the filament. Displacing the capacitive charge dissipation peak from the overshoot region by a longer pulse rising time was effective in reducing the random variations in the switching parameters. A smaller voltage step in the I-V sweep was effective in reducing the random variation in filament formation.Resistance switching ͑RS͒ phenomena in a variety of thin-film materials have recently attracted considerable attention for applications to the next generation of nonvolatile memory devices. 1-3 The unipolar RS proceeds by applying the same bias polarity and has been understood from the formation and rupture of the percolated conduction channels ͓conducting filaments ͑CFs͔͒ in several binary oxides, e.g., TiO 2 and NiO. 2,3 In the filamentary RS, improvement of the switching uniformity should be accomplished for memory device fabrication. One of the reasons for the nonuniform RS comes from the random nature of filament formation. Filament formation, accompanied by oxygen ion movement in most cases, is a very disordered process. [4][5][6] This results in the fluctuations of various switching parameters, such as the switching voltage and on and off currents. The other reason originated from the distortion of the stimulus signal for initiating RS. In pulse switching, input pulse distortion by the overshoot effect due to a short pulse rising time can cause a nonuniform RS. This article reports a method to overcome the overshoot effect on the set switching by using a current pulse with a longer rising time. In addition, in the voltage sweep switching, which is another common switching method, a smaller voltage step during the set switching reduced the random variation significantly.The preparation of a Pt/60 nm thick TiO 2 /Pt structured sample and a method for the RS of the sample are reported in detail elsewhere. 7,8 A current pulse pattern generator ͑PG, HP/Agilent 81110A͒ with various pulse rising ͑also falling͒ times ͑t r ͒ was used as a current pulse source for the first type of set switching experiments. The transient current at the moment of set switching using the PG was monitored using a digital oscilloscope ͑OSC, Tektronix 684C͒. For this current monitoring, the internal resistance of PG was set to 1 k⍀. The PG was programmed to obtain a peak current of 50 mA at the OSC considering the on-state resistance of the sample ͑ ϳ15 ⍀͒ and the internal resistance of the OSC ͑50 ⍀͒. A schematic diagram for the pulse switching setup is shown in the inset of Fig. 1f. Here, the monitored voltage in OSC ͑V R ͒ was converted into the sample current using the resistance of the OSC. For the second type of set switching experiments, a semiconductor parameter analyze...

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Interpretation of nanoscale conducting paths and their control in nickel oxide (NiO) thin films

Cited by 38 publications

References 13 publications

Fractal Dimension of Conducting Paths in Nickel Oxide (NiO) Thin Films During Resistance Switching

Fractal Dimension of Conducting Paths in Nickel Oxide (NiO) Thin Films During Resistance Switching

Filamentary Resistive Switching Localized at Cathode Interface in NiO Thin Films

Methods of Set Switching for Improving the Uniformity of Filament Formation in the TiO[sub 2] Thin Film

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