Low Power Electronics Association and Project

Tsukuba, Japan

Low Power Electronics Association and Project

Tsukuba, Japan
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Thien H.M.,University of Electro - Communications | Sugii N.,Low power Electronics Association and Project | Ishibashi K.,University of Electro - Communications
2014 SOI-3D-Subthreshold Microelectronics Technology Unified Conference, S3S 2014 | Year: 2014

This paper presents an ultra-low power receiver design at 920MHz. We proposed a receiver architecture, in which bias switch technique is applied to reduce power consumption significantly. The receiver was simulated and laid out on 65nm SOTB CMOS technology, consuming only 53uW at 0.6V supply voltage. It achieves a sensitivity of -82dBm with a data rate of 10 - 100 kbps. © 2014 IEEE.


Yoshida C.,Low power Electronics Association and Project | Min Lee Y.,Low power Electronics Association and Project | Ochiai T.,Low power Electronics Association and Project | Uehara Y.,Fujitsu Limited | Sugii T.,Low power Electronics Association and Project
Applied Physics Letters | Year: 2011

We investigated the dynamics of current-pulse-induced magnetization switching in magnetic tunnel junctions (MTJs) with antiferromagnetically and ferromagnetically coupled synthetic free layers through micromagnetic simulations. We found that a magnetic vortex is formed in thick upper ferromagnetic layers and plays an important role in magnetization switching in both types of synthetic free layers. Furthermore, higher thermal stability is observed in an MTJ with the ferromagnetically coupled free layer at an annealing temperature of 250 C. © 2011 American Institute of Physics.


Tada M.,Low Power Electronics Association and Project | Sakamoto T.,Low Power Electronics Association and Project | Banno N.,Low Power Electronics Association and Project | Okamoto K.,Low Power Electronics Association and Project | And 3 more authors.
IEEE Transactions on Electron Devices | Year: 2013

Cu-alloy active-electrode coupled with Ru-alloy inert electrode is proposed to improve the ON-state reliability of nonvolatile Cu atom switch. The high rupture temperature (T-{r}<400^{\circ}{\rm C}) of the nanometer-scale Cu bridge with high thermal resistance (R-{\rm th}) is realized by the Cu(AlTi)-alloy without increasing programming current. The anti-Cu diffusive Ru(Ta) alloy contributes to improve the retention of the ON-state at 150^{\circ}{\rm C} and endurance to {<}{10}4 cycles. The metallurgical prescription on the electrodes is a key to improve the stability of the nanometer-scale conducting bridge while keeping the switching power low. © 1963-2012 IEEE.


Tada M.,Low power Electronics Association and Project | Sakamoto T.,Low power Electronics Association and Project | Miyamura M.,Low power Electronics Association and Project | Banno N.,Low power Electronics Association and Project | And 3 more authors.
IEEE Transactions on Electron Devices | Year: 2012

A complementary atom switch (CAS) is proposed to realize low programming voltage and high off-state reliability for crossbar switch application. Two atom switches with bipolar operation are connected in series with opposite direction, in which the two atom switches work as a single element. The two off-state atom switches in the CAS complementarily divide voltage stress, greatly enlarging the off-state lifetime. The CAS is embedded in Cu BEOL on a 65-nm-node CMOS platform without degrading the CMOS and interconnect performances. The CAS using two atom switches is one of the candidates for realizing energy-efficient nonvolatile programmable switches. © 2012 IEEE.


Sakamoto T.,Low Power Electronics Association and Project | Tada M.,Low Power Electronics Association and Project | Okamoto K.,Low Power Electronics Association and Project | Hada H.,Low Power Electronics Association and Project
IEEE Transactions on Electron Devices | Year: 2012

Low-temperature characterization of electrical transport on atom switches has been performed to clarify operation and conducting mechanisms. The low resistive (ON) state (< 400 Ω) shows metallic conduction accompanied with a high residual resistance. In the high resistive (OFF) state (> 108), the resistance exponentially increases with decreasing temperature due to Poole-Frenkel conduction. In the intermediate range (105-107 Ω), the resistance has small temperature dependence since the electron tunneling via Cu residues in a solid electrolyte is dominant. The polymer solid electrolyte enables the complete collection of the Cu residues without degrading the electrolyte, resulting in forming-free operation and a high ON/OFF conductance ratio. © 2012 IEEE.


Takaura N.,Low power Electronics Association and Project
Materials Research Society Symposium Proceedings | Year: 2014

A charge-injection GeTe/Sb2Te3 superlattice phase change memory (PCM or PRAM) has been developed as a candidate for a non-volatile memory that replaces NAND flash memory. It differs from PRAM with the conventional material of GeSbTe, and is therefore named TRAM (topological switching random access memory). First principle calculations showed a resistance change in the GeTe/Sb2Te3 superlattice was enhanced by charge injection. The fabrication and analyses of a one-resistor TEG revealed that the superlattice structure was maintained after 1M endurance, which proved the occurrence of non-melting resistance change in TRAM. The reset current of TRAM was found to be less than 1/5 of that of conventional PRAM. Furthermore, TRAM enables a set -speed of 10 ns and reset -operation by DC-sweep to be achieved, which experimentally proved the atomic movement in TRAM can be enhanced by charge injection. Copyright © Materials Research Society 2014.


Tada M.,Low Power Electronics Association and Project | Okamoto K.,Low Power Electronics Association and Project | Banno N.,Low Power Electronics Association and Project | Sakamoto T.,Low Power Electronics Association and Project | Hada H.,Low Power Electronics Association and Project
IEEE Transactions on Electron Devices | Year: 2014

A diode-inserted complementary atom switch with two resistive-change junctions coupled with the diode-inserted gate is proposed. The atom switch serves the nonvolatile resistive-change junction, where the two atom switches are connected in series with opposite direction and transfer or cutoff the signals. The gate is placed between them through the diode, where back-end-of-the-line--{\rm Ta}-{{2}}{\rm O}-{5{-}x}- diode is directly stacked on the two of atom switches, achieving high rectifying separation of the gate. The developed device realizes the three-terminal operation and potentially enables to replace the CMOS routing switch composed of SRAM and transmission gate with nonvolatility. © 1963-2012 IEEE.


Yoshida C.,Low Power Electronics Association and Project | Ochiai T.,Low Power Electronics Association and Project | Sugii T.,Low Power Electronics Association and Project
Journal of Applied Physics | Year: 2012

We investigated the correlation between the microstructure and the electromagnetic properties of magnetic tunnel junctions (MTJs) with MgO barriers fabricated by direct sputtering and natural oxidation of the Mg layers. The MTJ with an oxidized Mg barrier contained amorphous phases in both the barrier and the CoFeB free layer and exhibited large interface fluctuations in both the CoFeB reference/MgO and MgO/CoFeB interfaces This had a significant influence on the low MR ratio and large switching current. Inserting a CoFe seed layer under the oxidized Mg barrier greatly improved the crystallization of the oxidized MgO which ultimately led to a higher MR ratio and lower switching current. In addition to the textured CoFeB/MgO/CoFeB structures, the sharp interface of the MgO barrier, low B content in the MgO barrier, and Fe-rich composition in the free layer are thought to be of key importance for ensuring high magneto-transport properties. © 2012 American Institute of Physics.


Yoshida C.,Low power Electronics Association and Project | Sugii T.,Low power Electronics Association and Project
IEEE International Reliability Physics Symposium Proceedings | Year: 2012

We examined the breakdown characteristics of naturally oxidized MgO barriers using a time dependent dielectric breakdown (TDDB) technique. We found that the positive bias dependence of the breakdown time can be explained using the E-model and negative bias dependence can be explained using the power-law model. This asymmetric nature of the oxidized MgO barrier was due to unoxidized Mg metal at the reference/barrier interface. We also estimated the lifetime expansion under pulse voltage stress by taking the Joule heating effects into account. © 2012 IEEE.


Takaura N.,Low power Electronics Association and Project | Ohyanagi T.,Low power Electronics Association and Project | Kitamura M.,Low power Electronics Association and Project | Tai M.,Low power Electronics Association and Project | And 8 more authors.
Digest of Technical Papers - Symposium on VLSI Technology | Year: 2013

A new charge injection Super-lattice Phase Change Memory was developed with optimized GeTe/Sb2Te3 deposition and state-of-the-art analytical techniques. First principle calculations showed the charge injection enhanced Ge atom movement for the first time. We achieved 0.46 V and 3.3 MA/cm2 reset and MLC programming. The stability of Super-lattice after 1E6 cycles was verified by thermal analysis characteristic to Ge 4-fold to Ge 6-fold transition. © 2013 JSAP.

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