Takumi Mikawa

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Nonvolatile memories with fast write operation at low voltage are required as storage devices to exceed flash memory performance. We develop an 8Mb multi-layered cross-point ReRAM macro with 443MB/S write throughput (64b parallel write per 17.2ns cycle), which is almost twice as fast as existing methods, using the fast-switching performance of TaOχ(More)
Highly reliable TaO<sub>x</sub> ReRAM has been successfully demonstrated. The memory cell shows stable pulse switching with endurance over 10<sup>9</sup> cycles, sufficient retention exceeding 10 years at 85degC. TaO<sub>x</sub> exhibits stable high and low resistance states based on the redox reaction mechanism, confirmed by HX-PES directly for the first(More)
A new oxygen diffusion reliability model for a high-density bipolar ReRAM is developed based on hopping conduction in filaments, which allows statistical predication of activation energy. The filament in the active cells is confirmed by EBAC and TEM directly for the first time. With optimized filament size, a 256-kbit ReRAM with long-term retention(More)
Resistive RAM (ReRAM) has been recently developed for applications that require higher speed and lower voltage than Flash memory is able to provide. One of the applications is micro-controller units (MCUs) or SoCs with several megabits of embedded ReRAM. Another is solid-state drives (SSDs) where a combination of higher-density ReRAM and NAND flash memory(More)
A novel iron oxide (Fe-O) ReRAM is proposed and its high-speed resistance-switching of 10 ns is demonstrated. The switching mechanism is confirmed as a redox reaction between Fe<sub>3</sub>O<sub>4</sub> and y-Fe<sub>2</sub>O<sub>3</sub>. Based on this model, we have achieved long-retention characteristics by introducing Zn atoms to suppress the reduction(More)
We demonstrate for the first time that the density of oxygen vacancy in a conductive filament plays a key role in ensuring data retention. We achieve very good retention results up to 100 hours at 150&#x00B0;C even under the low current operation due to the scaling of conductive filament size while retaining sufficiently high density of oxygen vacancy.
Despite the well-documented clinical significance of the Warburg effect, it remains unclear how the aggressive glycolytic rates of tumor cells might contribute to other hallmarks of cancer, such as bypass of senescence. Here, we report that, during oncogene- or DNA damage-induced senescence, Pak1-mediated phosphorylation of phosphoglycerate mutase (PGAM)(More)
Enhanced glycolysis in cancer, called the Warburg effect, is a well-known feature of cancer metabolism. Recent advances revealed that the Warburg effect is coupled to many other cancer properties, including adaptation to hypoxia and low nutrients, immortalisation, resistance to oxidative stress and apoptotic stimuli, and elevated biomass synthesis. These(More)