Voltage polarity dependent low-power and high-speed resistance switching in CoO resistance random access memory with Ta electrode

Shima, Hisashi; Takano, Fumiyoshi; Muramatsu, Hidenobu; Akinaga, H.; Tamai, Yasukatsu; Inque, Isao H.; Takagi, H.

doi:10.1063/1.2982426

Cited by 95 publications

(83 citation statements)

References 12 publications

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“…4,8,[19][20][21] In this section, the oxygen content of the bridge that appeared during forming will be discussed. Figure 3(a) shows a TEM image of the bridge region of the sample shown in Fig.…”

Section: B Oxygen Content Of Bridgementioning

confidence: 99%

“…However, their work was on the sample after the forming process. By using a serial resistor in the measurement circuit to suppress current overshoot during the forming process, 8,40 Fujii et al performed a real-time observation of the forming process of NiO. 42 A tiny conductive region called the "bridge" was formed during the abrupt decrease in resistance.…”

Section: Introductionmentioning

confidence: 99%

“…Investigations into developing a new type of nonvolatile memory called a resistance random access memory (ReRAM) are intensively conducted using this resistance switching. [1][2][3][4][5][6][7][8][9] The ReRAM has high functionalities such as high-speed access, high integration, low power consumption, and non-volatility. In addition, the fabrication method for producing ReRAMs is compatible to the CMOS process.…”

Section: Introductionmentioning

confidence: 99%

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In-situ transmission electron microscopy of conductive filaments in NiO resistance random access memory and its analysis

Fujii

Arita

Hamada

et al. 2013

Journal of Applied Physics

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We used thermal oxidization at various temperatures to prepare NiO/Pr-Ir for use in resistance random access memory (ReRAM) samples. In-situ transmission electron microscopy (TEM) was used to investigate the forming process of these ReRAM samples, where a needle-shaped top electrode of Pt-Ir was attached to the NiO/Pt-Ir ReRAM layer. The forming voltage initializing the NiO layer increased at an oxidization temperature of between 200 and 400 C. In this process, conductive bridges, which are thought to be conductive filaments of a ReRAM, appeared, and their sizes showed a correlation with the injection power. It was as small as about 300 nm 2 when the injection power was 10 À6 W. Energy dispersive X-ray spectroscopy was used to analyze the bridge, and it was experimentally confirmed that the oxygen content of the bridge was lower than that of the initial NiO layer. However, these bridges in the low resistance state did not show further ReRAM switching to the high resistance state inside of a TEM instrument. To check the reason of this result, we investigated samples outside of the TEM instrument, which had similar geometry to that of TEM specimens. They showed the ReRAM switching in air ambient but not in vacuum. Combining these results inside and outside of the TEM instrument, it can be concluded that the existence of oxygen around the conductive filament plays an important role. This supports the filament redox model on the ReRAM operation. V C 2013 American Institute of Physics.

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Section: B Oxygen Content Of Bridgementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In-situ transmission electron microscopy of conductive filaments in NiO resistance random access memory and its analysis

Fujii

Arita

Hamada

et al. 2013

Journal of Applied Physics

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“…For these experiments, the device was extracted and connected to the biasing chip thus removing the current selector [4]. The voltage applied to the CBRAM device for the forming step was around 3.7 V. We can conclude that the changes in element distribution and damage observed in the TEM result directly from the current surge and the associated joule effect within the chunk upon forming [5]. We observe here the failure mechanism where the Cu within the resistive layer aggregates in the device.…”

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confidence: 99%

In Situ Biasing of Conductive Bridge Resistive Memory Devices Observed in a Transmission Electron Microscope

et al. 2017

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Resistive memories are considered as the most promising candidate for the replacement of conventional flash memories [1]. Various types of resistive memories exist and they present improved capabilities in scalability, endurance, power consumption, operation speed and many other aspects. The mechanism responsible for their functioning has been widely studied and numerous models have been proposed but very few empirical measurements have been obtained so far. In-situ TEM is the most promising technique to obtain quantitative data at the atomic scale on a functioning device that can help us understand the dynamic mechanism responsible for their operation. However, at this time it is challenging to perform these experiments. In this presentation we will show our methodology to prepare specimens that are as close as possible to real devices in order to provide accurate measurements of the changes that are observed during resistive switching.For in situ TEM analysis, we used a Protochips Fusion biasing holder based on patterned silicon chip. Preparation was performed by coupling a liquid Gallium Focused Ion Beam (FIB) tool and Xenon plasma FIB tool [2]. A specific method has been developed to prepare a high quality TEM foil containing a functional device. The electrical properties of ion beam deposited materials have been measured and optimized for this method. Circuit editing techniques were used to preserve the device electrical properties during TEM foil preparation and ensure good connection with the system. After a conventional lift-out, extensive micromanipulation was used to position a thick specimen onto a biasing chip. The key aspect of this preparation is to place the chunk at a controlled angle relative to the membrane (around 20°) thus allowing thinning and low energy cleaning as a final step.Ex-situ electrical measurements were performed on a 500nm thick chunk connected to the biasing chip using the previously described preparation method (Fig.2a). We can clearly see the set and reset operation of the CBRAM sample comparable to conventional electrical characterization results obtained on the same samples [3]. We concluded that the device connected to the TEM in situ biasing chip was properly functioning, and that our FIB preparation was preserving electrical properties of the device.The sample was then thinned to TEM foil dimensions and STEM observations were performed in a FEI Titan Themis 200 keV (Fig.1b). STEM Energy Dispersive X-ray Spectroscopy (EDS) maps were obtained to observe the impact of resistive switching on element distribution. Deconvolution has been performed using conventional Cliff-Lorimer method and EDS maps were compared to the ones obtained on unbiased CBRAM samples. Strong modifications were detected on the CuTe2Ge layer (Fig.2b). Surprisingly, despite the extensive damage observed on the active layer after initial activation, in situ switching of the resistive memory was still possible within the TEM. For these experiments, the device was extracted and connected to the biasing chip...

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“…Changes to the chemical environment at the electrode interface have been reported to drive metal-oxide-metal (MOM) sandwich device performance. [19][20][21][22] For NiO, it has been proposed that an oxygen rich layer at the anode interface, controls the threshold switching of Pt-NiO-Pt system. 23 The presence of point and line defects, 24 composition inhomogeneity, 25 and atomic interdiffusion 26 at interfaces have been shown to have a significant impact on device properties.…”

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confidence: 99%

Role of interface structure and chemistry in resistive switching of NiO nanocrystals on SrTiO3

et al. 2014

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Nickel oxide (NiO) nanocrystals epitaxially grown on (001) strontium titanate (SrTiO3) single crystal substrates were characterized to investigate interface morphology and chemistry. Aberration corrected high angle annular dark field scanning transmission electron microscopy reveals the interface between the NiO nanocrystals and the underlying SrTiO3 substrate to be rough, irregular, and have a lower average atomic number than the substrate or the nanocrystal. Energy dispersive x-ray spectroscopy and electron energy loss spectroscopy confirm both chemical disorder and a shift of the energy of the Ti L2,3 peaks. Analysis of the O K edge profiles in conjunction with this shift, implies the presence of oxygen vacancies at the interface. This sheds light into the origin of the previously postulated minority carriers’ model to explain resistive switching in NiO [J. Sullaphen, K. Bogle, X. Cheng, J. M. Gregg, and N. Valanoor, Appl. Phys. Lett. 100, 203115 (2012)].

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Voltage polarity dependent low-power and high-speed resistance switching in CoO resistance random access memory with Ta electrode

Cited by 95 publications

References 12 publications

In-situ transmission electron microscopy of conductive filaments in NiO resistance random access memory and its analysis

In-situ transmission electron microscopy of conductive filaments in NiO resistance random access memory and its analysis

In Situ Biasing of Conductive Bridge Resistive Memory Devices Observed in a Transmission Electron Microscope

Role of interface structure and chemistry in resistive switching of NiO nanocrystals on SrTiO3

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