Tunnel current measurement of MgO and MgO/Fe/MgO nanoregions during TEM observation

Arita, Masashi; Okubo, Youhei; Hamada, K.; Takahashi, Yasuo

doi:10.1016/j.spmi.2008.01.020

Cited by 8 publications

(9 citation statements)

References 15 publications

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“…In situ transmission electron microscopy (TEM), where TEM observations and physical (e.g., electrical) measurements have been simultaneously performed, [27][28][29][30][31][32][33][34][35][36][37] has attracted a great deal of attention to satisfy this demand. The numbers of such studies using piezo-controlled TEM holders have been increasing in the past few years.…”

Section: Introductionmentioning

confidence: 99%

Analysis of resistance switching and conductive filaments inside Cu-Ge-S using in situ transmission electron microscopy

et al. 2012

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In situ transmission electron microscopy (TEM) was carried out to investigate the dynamics of resistance switching in a solid electrolyte, Cu-Ge-S. By applying voltage to Pt-Ir/Cu-Ge-S/Pt-Ir, where Pt-Ir constituted the electrodes, a deposit containing conductive filaments composed mainly of Cu was formed around the cathode. As voltage continued to be applied, the deposit grew and finally narrow conductive filaments made contact with the anode. This corresponded to resistance switching from high-to low-resistance states (HRS and LRS). By alternating the voltage, the deposit contracted toward the cathode and detached from the anode. The resistance immediately changed from LRS to HRS. By applying voltage, the deposit containing Cu-based filaments grew and shrank, and resistance switching occurred at the electrolyte-anode interface. This conductive filament-formation model, which was recently reported, was experimentally confirmed with TEM through dynamic observations of the deposit-containing filaments.

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Section: Introductionmentioning

confidence: 99%

Analysis of resistance switching and conductive filaments inside Cu-Ge-S using in situ transmission electron microscopy

et al. 2012

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“…16,24 The in-situ TEM observation system was composed of a custom-made TEM holder attached with a piezo actuator. [26][27][28][29] The TEM instrument we used was mainly a JEM-2010 microscope (200 kV, C s ¼ 0.5 mm, 10 À5 Pa) with a CCD video camera to record the TEM images. In the TEM holder, the wedge-shaped ReRAM sample described above and a tip-shaped counter electrode made of Pr-Ir working as a TE were placed.…”

Section: Methodsmentioning

confidence: 99%

“…One method is in-situ transmission electron microscopy (TEM), where electric measurements and geometric and crystallographic observations can be simultaneously performed. [26][27][28][29] have been investigated by in-situ TEM. The first one was PCMO which shows the bipolar switching.…”

Section: Introductionmentioning

confidence: 99%

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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“…The system is composed of a custom-made TEM holder, a control system for the piezo actuator, a current measurement unit, and a CCD camera system. 12,16 The TEM instrument was a JEM 2010 microscope (200 kV, Cs ¼ 0.5 mm), whose vacuum was about 10 À 5 Pa. The TEM holder Fig.…”

Section: Methodsmentioning

confidence: 99%

“…9 Though a single bridge-like path was confirmed, it is necessary to research inside the bridge for observing realtime filament formation. In situ transmission electron microscopy (TEM) simultaneously performed with physical (e.g., electrical) measurements [10][11][12] has attracted a great amount of attention to satisfy this demand. The number of such studies using piezo TEM holders has been increasing in the past few years.…”

Section: Introductionmentioning

confidence: 99%

I-V measurement of NiO nanoregion during observation by transmission electron microscopy

Fujii

Arita

Hamada

et al. 2011

Journal of Applied Physics

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Conduction measurements with simultaneous observations by transmission electron microscopy (TEM) were performed on a thin NiO film, which is a candidate material for resistance random access memories (ReRAMs). To conduct nanoscale experiments, a piezo-controlled TEM holder was used, where a fixed NiO sample and a movable Pt-Ir counter electrode were placed. After the counter electrode was moved to make contact with NiO, I-V measurements were carried out from any selected nanoregions. By applying a voltage of 2 V, the insulating NiO film was converted to a low resistance film. This phenomenon may be the "forming process" required to initialize ReRAMs. The corresponding TEM image indicated a structural change in the NiO layer generating a conductive bridge with a width of 30-40 nm. This finding supports the "breakdown" type forming in the so-called "filament model" of operation by ReRAMs. The inhomogeneity of resistance in the NiO film was also investigated.

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Tunnel current measurement of MgO and MgO/Fe/MgO nanoregions during TEM observation

Cited by 8 publications

References 15 publications

Analysis of resistance switching and conductive filaments inside Cu-Ge-S using in situ transmission electron microscopy

Analysis of resistance switching and conductive filaments inside Cu-Ge-S using in situ transmission electron microscopy

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

I-V measurement of NiO nanoregion during observation by transmission electron microscopy

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