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ABSTRACT: A Nd:YAG (neodymium-doped yttrium aluminum garnet) laser is environmentally safe, due to the absence of any poisonous or hazardous gases, and also economical, without the need for expensive gases. We can thus expect a safe and low cost REBa<sub>2</sub>Cu<sub>3</sub>O y (REBCO)-coated conductor fabrication process by using an Nd:YAG laser. We investigated the fabrication of YBa<sub>2</sub>Cu<sub>3</sub>O y (YBCO) films using a PLD method with a fourth harmonic Nd:YAG laser. The YBCO films showed good superconducting properties; for example, on SrTiO<sub>3</sub> single crystalline substrates, T <sub>c</sub> and J <sub>c</sub> were about 90 K and 2.5 MA/cm<sup>2</sup>, respectively, at 77 K. In order to enhance J <sub>c</sub> in magnetic fields, BaSnO<sub>3</sub> was doped into YBCO films by means of a combinatorial Nd:YAG-PLD method. The combinatorial method enabled the growth and study of a library of samples ranging from pure-YBCO to BSO-doped-YBCO. We demonstrated rapid optimization of BaSnO<sub>3</sub> content by the combinatorial method and concluded that the optimal BSO content was around 3.6 wt%. In addition, in order to enhance material yield of the Nd:YAG-PLD method, we optimized the oxygen pressure and distance between the target and substrate. On a substrate with dimensions of 10 × 10 mm<sup>2</sup>, the material yield of a YBCO film reached about 19.0%. These results suggest that the Nd:YAG-PLD method is promising for forming YBCO-coated conductors.
IEEE Transactions on Appiled Superconductivity 07/2011; · 1.04 Impact Factor
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06/2011: pages 57 - 65; , ISBN: 9781118144121
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ABSTRACT: Wafer-level testing allows detection of manufacturing errors and removes non functional devices early in the fabrication process. It is commonly performed by placing a probe card directly above a device under test (DUT) and establishing a mechanical contact between them by means of an array of probes. This is an invasive technique that may damage fragile low-k dielectric layers and deform pads or bumps. More importantly, it is very difficult to flip thinned wafers face up for probing if they were earlier positioned face down for back grinding. Additional difficulty in handling of thinned wafers arises if dies have to be flipped again for bumping. One solution to above problems is wireless probing. With a number of proposed techniques for establishing high-speed inductive-coupling data links and measuring DC analog signal wirelessly, the largest remaining obstacle to non-contact wafer-level testing is supplying power to the DUT. This is because wireless power transfer solutions reported earlier do not provide an output power that is sufficient for testing modern high performance devices.This paper presents an inductive power transfer system that is capable of delivering up to 6W of DC power to the on-chip load. The system is partitioned into 8 power transfer channels, each containing two cir cuits: a power transmitter implemented in the probe card, and an on-chip power receiver. This paper focuses on the design of the power receiver, as the receiver performance limits the output power of the whole system.
Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2011 IEEE International; 03/2011
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ABSTRACT: A small-size inductive-coupling dc voltage transceiver for highly-parallel wafer-level testing is experimentally demonstrated in 90-nm CMOS technology, which can reduce the total cost of a low-price IC by 18%. In order to carry out dc tests, the proposed transceiver outputs dc voltage to the die-under-test (DUT) without any area-consuming digital circuits. In addition, digital calibration with digital feedback channel which calibrates the output dc voltage enables the removal of calibration circuits on the DUT. All of the circuits for dc tests are implemented into the area of an inductor (100 μm ×100 μm). The proposed dc voltage transmission is successfully demonstrated with 6-bit resolution.
IEEE Journal of Solid-State Circuits 11/2010; · 3.23 Impact Factor
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ABSTRACT: This paper presents a power reduction scheme and an area reduction scheme in inductive-coupling programmable bus for NAND flash memory stacking. A channel arrangement scheme using three coils enables random access for memory read and memory write. Transmit power is reduced by 47% compared to a previous design with shields. A coil layout style, herein noted as XY coil, allows for the coils to interleave with logic interconnections, resulting in area reduction of 91% relative to at the expense of only 17% transmit power increase. Relayed data transmission at 1.6 Gb/s and BER <; 10<sup>-12</sup> is achieved.
Circuits and Systems I: Regular Papers, IEEE Transactions on 10/2010; · 1.97 Impact Factor
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ABSTRACT: Representation and evaluation methods for statistically predicting organ shapes from neighboring organ shapes are described. In order to fully utilize the constraints on interrelations of multiple organ shapes, various extents of sub-shapes of organs are considered based on their proximity instead of just using the whole organ shapes. The prediction power are evaluated for various extents of sub-shapes and enhanced by their integration. Experimental results using shape datasets of several organs in the abdominal domain demonstrate the effective of the proposed methods.
Software Engineering and Data Mining (SEDM), 2010 2nd International Conference on; 07/2010
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S. Kawabata,
M. Nakura,
S. Yamazaki,
T. Shibuya,
Y. Inoue,
J. Onishi,
Y. Tabuchi,
Y. Tamai,
Y. Yaoi,
K. Ishihara, [......],
N. Fukuda,
H. Kurihara, Y. Yoshida,
Y. Kokaze,
Y. Nishioka,
K. Suu,
K. Nakayama,
A. Kitagawa,
S. Ohnishi,
N. Awaya
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ABSTRACT: This paper presents the process integration and device technology for the Resistance RAM(RRAM) memory array using a CoOx film and a recess structure as a resistor, which is capable of low voltage, high speed and low current operation. The resistance of the CoOx film and its uniformity are strongly dependent on the film quality, which is optimized by controlling the O<sub>2</sub> gas flow rate during the film deposition. We demonstrate the basic write and read operation of the 128Kbits memory array by developing the novel process integration technology and optimizing the test algorism.
Memory Workshop (IMW), 2010 IEEE International; 06/2010
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M Takamura,
M Mukaida,
S Horii,
A Ichinose,
R Kita,
K Matsumoto, Y Yoshida,
M Namba,
S Awaji,
K Watanabe,
R Teranishi,
N Mori
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ABSTRACT: A relationship between microstructures of YBa2Cu3Oy (Y123) films with two-dimensional artificial pinning centers (2D APCs) and their critical current density (Jc), especially under matching fields (B), is discussed. Using a pulsed laser deposition (PLD) method, c-axis in-plane aligned a-axis-oriented Y123/Pr123 multilayer films were grown on substrates. The Pr123 interlayer distance was changed by controlling a target shape and its rotation speed in the PLD process. The multilayer structure was observed in cross-sectional transmission electron microscopy images. Critical temperatures of the films decrease as the Y123 layer becomes thinner. The magnetic field (B) dependence of Jc showed that the interlayers act as 2D APCs in multilayer films. The matching effects were observed in two ways: curves and irreversibility lines.
Superconductor Science and Technology 03/2010; 23(4):045023. · 2.66 Impact Factor
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ABSTRACT: An inductive-coupling programmable bus for NAND flash memory access in solid state drive (SSD) is presented. Compared to the conventional SSD, this wireless interface using relayed transmission reduces power consumption to 1/2, I/O circuit-layout area to 1/40, and achieves a data rate of 2 Gb/s in 0.18 ¿m CMOS process. In addition, since this wireless interface enables one package to contain 64 chips, the number of packages is reduced to 1/8.
IEEE Journal of Solid-State Circuits 02/2010; · 3.23 Impact Factor
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ABSTRACT: Effects of growth temperatures in epitaxial ErBa2Cu3O7−δ films with one-dimensional nanorods were discussed from their microstructures and superconducting properties. c-axis-oriented BaNb2O6-doped ErBa2Cu3O7−δ films were grown on (100)-oriented SrTiO3 substrates grown at 710 and 760 °C by pulsed-laser deposition. Atomic force microscopy analysis showed that film surface steps on the three-dimensional islands increased with decreasing growth temperature (TS). Then, nanorod morphologies were also changed by TS. Ba(Er0.5Nb0.5)O3 nanorods were observed clearly in transmission electron microscopy images of the films. The nanorods were thinner and denser at a lower TS under a nominal BaNb2O6 (BNO) doping concentration. In the case of TS = 710 °C, the diameter and number density of nanorods with 1.5 wt%BNO doping were 4–6 nm and 2.6 × 1011 cm−2, respectively. Furthermore, the nanorods could effectively act as c-axis-correlated pinning centers in the film grown at a lower TS. Consequently, the pinning effects were controlled by nanorod morphologies through varying the TS.
Superconductor Science and Technology 12/2009; 23(2):025017. · 2.66 Impact Factor
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T. Sekine,
R. Fujimoto,
Y. Takamatsu,
M. Nakamura,
T. Hirakawa,
M. Ishii,
T. Yasuda,
M. Hayashi,
H. Itoh,
Y. Wada,
T. Imayama,
T. Oomoto,
Y. Ogasawara,
S. Saigusa,
M. Yano,
M. Nishikawa,
H. Yoshida, Y. Yoshida,
K. Yoshioka,
N. Itoh
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ABSTRACT: This paper presents the first published single-chip RF tuner / OFDM demodulator for a mobile digital TV application (1-segment broadcasting). To improve the minimum sensitivity, spurious signal suppression techniques are proposed. The single-chip RF tuner / OFDM demodulator using the proposed spurious signal suppression techniques is fabricated using 90 nm CMOS technology and total die size is 3.26 mm times 3.26 mm. By suppressing undesired spurious signals, the minimum sensitivity of -98.6 dBm is achieved. The optimum current consumption is chosen for the RF tuner by using an adaptive control, the power consumption of the proposed single-chip receiver is only 60 mW in medium-signal receiving mode.
ESSCIRC, 2009. ESSCIRC '09. Proceedings of; 10/2009
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S. Saito,
Y. Kohama,
Y. Sugimori,
Y. Hasegawa,
H. Matsutani,
T. Sano,
K. Kasuga, Y. Yoshida,
K. Niitsu,
N. Miura,
T. Kuroda,
H. Amano
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ABSTRACT: MuCCRA-cube is a scalable three dimensional dynamically reconfigurable processor. By stacking multiple dies connected with inductive-coupling links, the number of PE array can be increased so that the required performance is achieved. A prototype chip with 90 nm CMOS process consisting of four dies each of which has a 4 times 4 PE array was implemented. The vertical link achieved 7.2Gb/s/chip, and the average execution time is reduced to 31% compared to that using a single chip.
Field Programmable Logic and Applications, 2009. FPL 2009. International Conference on; 10/2009
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ABSTRACT: It is known that columnar defects comprised of self-organized BaZrO<sub>3</sub> (BZO) nanorods within REBa<sub>2</sub>Cu<sub>3</sub>O y (REBCO) films are attractive as c -axis correlated pinning centers. On the other hand, we have fabricated high-J<sub>c</sub> Sm<sub>1+x</sub>Ba<sub>2-x</sub>Cu<sub>3</sub>O<sub>y</sub> (SmBCO) films including nanosized low-T<sub>c</sub> phases by using the low-temperature growth (LTG) technique. In this study, BZO nanorods were added to the LTG-SmBCO film for a further enhancement of the magnetic flux pinning. Additionally, we also deposited a conventional PLD-SmBCO film including BZO nanorods and discussed differences of the flux pinning properties and microstructures between LTG- and PLD-SmBCO films. In a cross-sectional transmission electron microscopy (TEM) image of the BZO doped PLD-SmBCO film, we could see the self-organized BZO nanorods were about 10 nm in diameter, extending along the c -axis of the film. In contrast, in the BZO doped LTG-SmBCO film, the high density BZO nanorods with smaller diameters tended to be short columns and tilted against the c -axis direction. These facts can be attributed to a suppression of the surface diffusion length of adatoms and/or an increase of nucleation frequency due to the low substrate temperature during the growth of the BZO doped LTG-SmBCO film. Furthermore, we concluded that differences of superconducting properties between the BZO doped PLD- and LTG-SmBCO films might be attributed to the difference in the number density of BZO nanorods which generated lattice strain around them.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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ABSTRACT: New Ti-Sn intermetallic compound of Ti<sub>2</sub>Sn<sub>3</sub> could be easily synthesized at both of diffusion couple and powder mixture. It was found that Ti<sub>2</sub>Sn<sub>3</sub> is very brittle and easily deformed to fine powders. This new high Sn-based compound could be used for an additional Ti and Sn source for the bronze processed (Nb,Ti)<sub>3</sub>Sn wires. The hybrid bronze processed wires are demonstrated with additional Ti<sub>2</sub>Sn<sub>3</sub> modules in the bronze matrix. Significantly thick (Nb,Ti)<sub>3</sub>Sn layers were formed. Although Nb cores still remained in the center of filaments, (Nb,Ti)<sub>3</sub>Sn layers had no apparent gradient of Sn and Ti concentrations. We found the formation of (Cu,Nb)SnTi phases along (Nb,Ti)<sub>3</sub>Sn filaments. After heat treatment, no large Kirkendall voids were observed in the position filled up Ti<sub>2</sub>Sn<sub>3</sub> powders. Fine tau1-CuSn<sub>3</sub>Ti<sub>5</sub> precipitates are dispersed and they may behave as the reinforcement for the bronze matrix. It might resemble the effect of the ODS copper. The T <sub>c</sub> of hybrid bronze processed wires made with additional Ti<sub>2</sub>Sn<sub>3</sub> modules is comparable with that of the commercially bronze processed wires, which is about 17.5 K.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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ABSTRACT: The irreversibility temperatures were measured for a -axis oriented and c -axis in-plane aligned Y123/Pr123 multilayer films in various magnetic fields. Pr123 layers act as two-dimensional (planer) c -axis correlated artificial pinning centers (APCs) in the multilayer films. In the irreversibility field-temperature ( B <sub>irr</sub> - T ) curves, the crossover was observed near matching field B <sub>phi</sub> for the multilayer films, when the magnetic fields were applied parallel to the c -axis of the film ( B // c ). It is suggested the vortex state in Y123 films with two-dimensional APCs is Bose glass below the crossover field. The B <sub>irr</sub> - T curves under B // a shifted toward lower temperature and magnetic field regions.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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ABSTRACT: We compared J <sub>C</sub> properties of i) Pure ErBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-delta</sub> films on BaZrO<sub>3</sub> buffered MgO substrates, ii) Pure ErBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-delta</sub> films on SrTiO<sub>3</sub> substrates, iii) BaSnO<sub>3</sub> doped ErBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-delta</sub> films on SrTiO<sub>3</sub> substrates, and iv) BaSnO<sub>3</sub> doped ErBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-delta</sub> films on BaSnO<sub>3</sub> buffered MgO substrates. The lowest J <sub>C</sub> was obtained from pure ErBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-delta</sub> films on SrTiO<sub>3</sub> substrates because of low dislocation densities, c-axis correlated pinning properties are obtained from pure ErBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-delta</sub> films on BaSnO<sub>3</sub> buffered MgO substrates indicating there exist dislocations along the c-axis of the films. The highest J <sub>C</sub> was obtained from BaSnO<sub>3</sub> doped ErBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-delta</sub> films on SrTiO<sub>3</sub> substrates. Almost the same J <sub>C</sub> was obtained from BaSnO<sub>3</sub> doped ErBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-delta</sub> films on BaSnO<sub>3</sub> buffered MgO substrates. 2 wt% BaSnO<sub>3</sub> doping into ErBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-delta</sub> films on BaSnO<sub>3</sub> buffered MgO substrates are very effective to enhance J <sub>C</sub> <sub>S</sub> of the films at a high magnetic field.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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ABSTRACT: The crystal defects of the nano-scale, which are called artificial pinning centers (APCs), were successfully introduced into high-temperature superconductors (HTS) by nanotechnology, in order to strongly pin the quantized vortices. Critical current densities Jc of the HTS films were dramatically improved by APCs whose dimensions were controlled. By this method, the in-field Jc (77 K) of the high-quality, epitaxial films was improved by one order of magnitude or more compared with the values of the past. A current outline of the research is described in this paper.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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S. Funaki, Y. Yoshida,
Y. Ichino,
T. Ozaki,
T. Harada,
Y. Takai,
K. Matsumoto,
A. Ichinose,
M. Mukaida,
R. Kita,
S. Horii
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ABSTRACT: For an improvement of Jc under applied magnetic fields, an addition of BaZrO<sub>3</sub> (BZO) nanorods into REBa<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub>(REBCO) films is actively discussed. However, the growth mechanisms of the BZO nanorods are still evidently unexplained. In this study, in order to control the growth of BZO nanorods in REBCO films, we fabricated the Sm<sub>1+x</sub>Ba<sub>2-x</sub>Cu<sub>3</sub>O<sub>y</sub> (SmBCO) films containing BZO by conventional pulsed laser deposition (PLD-Sm+BZO) and vapor-liquid-solid technique (VLS-Sm+BZO). The self field Jc 's of PLD- and VLS-Sm+BZO films showed 1.3 MA/cm<sup>2</sup> and 1.2 MA/cm<sup>2</sup>, respectively. However, magnetic field dependence of the Jc for the VLS-Sm+BZO film was twice as high as that of the PLD-Sm+BZO film at 77 K, B = 5 T. From a microstructure analysis, we found the BZO nanorods in VLS-Sm+BZO film grew nearly straight along the c-axis of the SmBCO.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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ABSTRACT: Recently increasing the J <sub>c</sub> at higher magnetic field can be accomplished by introducing artificial pinning center (APC) into REBCO coated conductor and films. In particular, in impurity additions, nano-BaZrO<sub>3</sub> (BZO) rods in PLD-YBCO and GdBCO coated conductor have been investigated for c -axis correlated flux pinning. We have reported the high J <sub>c</sub> SmBCO and (Nd,Eu,Gd)BCO films and coated conductor using usual PLD, low temperature growth (LTG) and Vapor-liquid-solid growth (VLS) technique. In this research we studied the controlling the nanorods BZO growth mechanism by initial deposition of nanodots on the surface for improving the J <sub>c</sub> at magnetic field. REBCO+BZO film are found to have superior performance in magnetic field at all field orientations, suggesting the presence of BZO-rods with optimized shape and density caused increasing BZO-dots at nuclear growth. The present work has confirmed that the control of APC initial growth is a promising technique to produce flux pinning center.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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ABSTRACT: We report that (Nd,Eu,Gd)Ba<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub> (NEG) films grown by low temperature growth (LTG) technique exhibit excellent superconducting properties in magnetic fields. In this study, we aim to improve the superconducting properties of NEG films by means of a modified LTG technique (mLTG) in which the surface of a highly c -axis oriented NEG seed layer is decorated by BaZrO<sub>3</sub> (BZO) nanodots and an NEG upper layer on the seed layer is deposited at relatively low substrate temperature by using a BZO doped NEG123 target. From magnetic field and angular dependence of J <sub>c</sub> , even J <sub>c</sub> peak around B // c -axis of an LTG-NEG films including BZO was larger than that of LTG-NEG without BZO. Furthermore, the mLTG-NEG films showed larger J <sub>c</sub> peak than the LTG-NEG films with BZO and the J <sub>c</sub> peak increased with increasing the BZO nanodots density. TEM images clarified that these films included BZO nanorods with a diameter of 5 ~ 10 nm and the number density increased by introducing the BZO nanodots. Therefore, we concluded that the mLTG enabled to improve the superconducting properties due to control the configuration of BZO nanorods in the films.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
