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Atomic View of Filament Growth in Electrochemical Memristive Elements.

Lv H, Xu X, Sun P, Liu H, Luo Q, Liu Q, Banerjee W, Sun H, Long S, Li L, Liu M - Sci Rep (2015)

Bottom Line: The physical nature of the formed filament was characterized by high resolution transmission electron microscopy.Copper rich conical filament with decreasing concentration from center to edge was identified.Based on these results, a clear picture of filament growth from atomic view could be drawn to account for the resistance modulation of oxide electrolyte based electrochemical memristive elements.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Microelectronics Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China.

ABSTRACT
Memristive devices, with a fusion of memory and logic functions, provide good opportunities for configuring new concepts computing. However, progress towards paradigm evolution has been delayed due to the limited understanding of the underlying operating mechanism. The stochastic nature and fast growth of localized conductive filament bring difficulties to capture the detailed information on its growth kinetics. In this work, refined programming scheme with real-time current regulation was proposed to study the detailed information on the filament growth. By such, discrete tunneling and quantized conduction were observed. The filament was found to grow with a unit length, matching with the hopping conduction of Cu ions between interstitial sites of HfO2 lattice. The physical nature of the formed filament was characterized by high resolution transmission electron microscopy. Copper rich conical filament with decreasing concentration from center to edge was identified. Based on these results, a clear picture of filament growth from atomic view could be drawn to account for the resistance modulation of oxide electrolyte based electrochemical memristive elements.

No MeSH data available.


Related in: MedlinePlus

Real-time regulation of the current flow.(a) The I-V curve of the common SET operation with VS swept from 0 ~ 1.3 V and VG constantly biased at 1.5 V. (b) The I-V curve of the RESET process with VD sweeping. (c) The SET curve for the varied VG programing scheme. VS is constantly biased with a voltage of 2 V and VG varies from 0 V to 1.5 V with an increasing rate of 0.005 V per step. (d) The IDS dependence of VG in the RESET process, with VD kept at 2 V and VS at ground.
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f1: Real-time regulation of the current flow.(a) The I-V curve of the common SET operation with VS swept from 0 ~ 1.3 V and VG constantly biased at 1.5 V. (b) The I-V curve of the RESET process with VD sweeping. (c) The SET curve for the varied VG programing scheme. VS is constantly biased with a voltage of 2 V and VG varies from 0 V to 1.5 V with an increasing rate of 0.005 V per step. (d) The IDS dependence of VG in the RESET process, with VD kept at 2 V and VS at ground.

Mentions: Digging the growth kinetics of filament is always of research interest. The commonly observed fast resistive switching during programming dramatically increases the difficulty in capturing detailed information about filament growth. Figure 1a shows the I-V curve of a typical SET operation (from high resistance state-HRS, to low resistance state-LRS) of a Cu/HfO2/Pt device, in which VS was swept from 0 ~ 1.3 V and VG was constantly biased at 1.5 V (detailed information on device fabrication and test conditions could be found in Figure S1). This is a widely used approach to program the electrochemical metallization devices. As VS increased to around 0.5 V, the IDS suddenly jumped from 0.1 nA to 200 μA, which was the saturation current of the transistor under VG = 1.5 V, indicating a sharp decrease in the cell resistance from several GΩ to hundreds of Ω. This fast resistive switching was resulted from positive feedback from the local electrical field2324. Once the filament started to grow, the electrical field on the tip was enhanced due to the point discharge effect and the reduction of the distance from the filament tip to the counter electrode. As a result, an abrupt transition was observed. Figure 1b shows the I-V curve of the RESET process (from LRS to HRS) as VD was swept. The IDS decreased with VD, showing that the cell resistance was highly dependent on the RESET voltage. The RESET process corresponded to a joule heat assisted dissolution process in the filament, starting from its thinnest point25.


Atomic View of Filament Growth in Electrochemical Memristive Elements.

Lv H, Xu X, Sun P, Liu H, Luo Q, Liu Q, Banerjee W, Sun H, Long S, Li L, Liu M - Sci Rep (2015)

Real-time regulation of the current flow.(a) The I-V curve of the common SET operation with VS swept from 0 ~ 1.3 V and VG constantly biased at 1.5 V. (b) The I-V curve of the RESET process with VD sweeping. (c) The SET curve for the varied VG programing scheme. VS is constantly biased with a voltage of 2 V and VG varies from 0 V to 1.5 V with an increasing rate of 0.005 V per step. (d) The IDS dependence of VG in the RESET process, with VD kept at 2 V and VS at ground.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4543950&req=5

f1: Real-time regulation of the current flow.(a) The I-V curve of the common SET operation with VS swept from 0 ~ 1.3 V and VG constantly biased at 1.5 V. (b) The I-V curve of the RESET process with VD sweeping. (c) The SET curve for the varied VG programing scheme. VS is constantly biased with a voltage of 2 V and VG varies from 0 V to 1.5 V with an increasing rate of 0.005 V per step. (d) The IDS dependence of VG in the RESET process, with VD kept at 2 V and VS at ground.
Mentions: Digging the growth kinetics of filament is always of research interest. The commonly observed fast resistive switching during programming dramatically increases the difficulty in capturing detailed information about filament growth. Figure 1a shows the I-V curve of a typical SET operation (from high resistance state-HRS, to low resistance state-LRS) of a Cu/HfO2/Pt device, in which VS was swept from 0 ~ 1.3 V and VG was constantly biased at 1.5 V (detailed information on device fabrication and test conditions could be found in Figure S1). This is a widely used approach to program the electrochemical metallization devices. As VS increased to around 0.5 V, the IDS suddenly jumped from 0.1 nA to 200 μA, which was the saturation current of the transistor under VG = 1.5 V, indicating a sharp decrease in the cell resistance from several GΩ to hundreds of Ω. This fast resistive switching was resulted from positive feedback from the local electrical field2324. Once the filament started to grow, the electrical field on the tip was enhanced due to the point discharge effect and the reduction of the distance from the filament tip to the counter electrode. As a result, an abrupt transition was observed. Figure 1b shows the I-V curve of the RESET process (from LRS to HRS) as VD was swept. The IDS decreased with VD, showing that the cell resistance was highly dependent on the RESET voltage. The RESET process corresponded to a joule heat assisted dissolution process in the filament, starting from its thinnest point25.

Bottom Line: The physical nature of the formed filament was characterized by high resolution transmission electron microscopy.Copper rich conical filament with decreasing concentration from center to edge was identified.Based on these results, a clear picture of filament growth from atomic view could be drawn to account for the resistance modulation of oxide electrolyte based electrochemical memristive elements.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Microelectronics Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China.

ABSTRACT
Memristive devices, with a fusion of memory and logic functions, provide good opportunities for configuring new concepts computing. However, progress towards paradigm evolution has been delayed due to the limited understanding of the underlying operating mechanism. The stochastic nature and fast growth of localized conductive filament bring difficulties to capture the detailed information on its growth kinetics. In this work, refined programming scheme with real-time current regulation was proposed to study the detailed information on the filament growth. By such, discrete tunneling and quantized conduction were observed. The filament was found to grow with a unit length, matching with the hopping conduction of Cu ions between interstitial sites of HfO2 lattice. The physical nature of the formed filament was characterized by high resolution transmission electron microscopy. Copper rich conical filament with decreasing concentration from center to edge was identified. Based on these results, a clear picture of filament growth from atomic view could be drawn to account for the resistance modulation of oxide electrolyte based electrochemical memristive elements.

No MeSH data available.


Related in: MedlinePlus