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[Author] Hiroshi KIMURA(5hit)

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  • Electric Field Dependence of Eigenstates in Quantum Wells with Arbitrary Potential Distribution

    Tanroku MIYOSHI  Hiroshi KIMURA  Matsuto OGAWA  

     
    LETTER-Quantum Electronics

      Vol:
    E70-E No:4
      Page(s):
    297-299

    As a general approach to analyse the field effects on a quantum well with arbitrary potential distribution, a method based upon finite element is presented. The field dependence of the resonant width and the effective energy gap is analysed for quantum wells with potential deformation around the center of wells.

  • Suppression of Ground Radar Interference in JERS-1 SAR Data

    Hiroshi KIMURA  Takashi NAKAMURA  Konstantinos P. PAPATHANASSIOU  

     
    PAPER-Sensing

      Vol:
    E87-B No:12
      Page(s):
    3759-3765

    JERS-1 L-band SAR data can be, especially over urban areas affected by ground radar interferences. For most of the applications of the data the interferences should be suppressed. Notch filtering during image correlation process is one of the straightforward ways to do this. However, lower the threshold is, more signals from earth surface is eliminated. In this paper, a probability density function (PDF's) model of the ground radar interference signal is worked out from experimental data, and used for the suppression of interferences and the preservation of backscattered signals. The validity of the model is confirmed against real SAR data, and a general filter threshold--applicable to all JERS-1 SAR data--without any conditions is proposed.

  • Soft-Error Study of DRAMs with Retrograde Well Structure by New Evaluation Method

    Yoshikazu OHNO  Hiroshi KIMURA  Ken-ichiro SONODA  Tadashi NISHIMURA  Shin-ichi SATOH  Hirokazu SAYAMA  Shigenori HARA  Mikio TAKAI  Hirokazu MIYOSHI  

     
    PAPER-Device Technology

      Vol:
    E77-C No:3
      Page(s):
    399-405

    A new method for the DRAM soft-error evaluation was developed. By using a focused proton microprobe as a radiation source, and scanning it on a memory cell plane, local sensitive structure of memory cells against soft-errors could be investigated with a form of the susceptibility mapping. Cell mode and bit-line mode soft-errors could be clearly distinguished by controlling the incident location and the proton dose, and it was also found that the incident beam within 4 µm around the monitored memory cell caused the soft-error. The retrograde well formed by the MeV ion implantation technology was examined by this method. It was confirmed that the B+ layers in the retrograde well were a sufficient barrier against the charge collection. The generation rate of the electron-hole pairs and the charge collection into n+ layers with a retrograde well and a conventional well were estimated by the device simulator, and were explained the experimental results.

  • A 10-b 300-MHz Interpolated-Parallel A/D Converter

    Hiroshi KIMURA  Akira MATSUZAWA  Takashi NAKAMURA  Shigeki SAWADA  

     
    PAPER

      Vol:
    E76-C No:5
      Page(s):
    778-786

    This paper describes a monolithic 10-b A/D converter that realized a maximum conversion frequency of 300 MHz. Through the development of the interpolated-parallel scheme, the severe requirement for the transistor Vbe matching can be alleviated drastically, which improves differential nonlinearity (DNL) significantly to within 0.4 LSB. Furthermore, an extremely small input capacitance of 8 pF can be attained, which translates into better dynamic performance such as SNR of 56 dB and THD of 59 dB for an input frequency of 10 MHz. Additionally, the folded differential logic circuit has been developed to reduce the number of elements, power dissipation, and die area drastically. Consequently, the A/D converter has been implemented as a 9.0 4.2-mm2 chip integrating 36K elements, which consumes 4.0 W using a 1.0-µm-rule, 25-GHz ft, double-polysilicon self-aligned bipolar technology.

  • Co-planar Josephson Junction Using Nonsuperconductive YBaCuO Formed on Very Locally Damaged Substrate by FIB

    Yunnghee KIM  Yoshihisa SOUTOME  Hiroshi KIMURA  Yoichi OKABE  

     
    PAPER-Three terminal devices and Josephson Junctions

      Vol:
    E78-C No:5
      Page(s):
    471-475

    A YBaCuO-Nonsuperconductive YBaCuO-YBaCuO coplanar Josephson junction has been fabricated, using Nonsuperconductive YBaCuO thin film deposited on an MgO(100) substrate with intentional and very local damage which was created by Focused Ion Beam. The YBaCuO grown on the damaged section of the substrate turned out to be non-superconductor, due to implanted Ga ions and the change in the crystal quality, facilitating formation of an S-N-S junction. We found the important fact that the critical current density decreased exponentially with inverse of the junction length which was changed from 0.2 to 1 µm, and that Ga ion was detected in the thin films of the junctions, and that the thin films of the junctions were formed by a mixture of an amorphous, a polycrystal and a crystal, which is confirmed by Transmission Electron Diffraction. And the damaged substrate gave rise to Ga segregation and the mixed crystal, which played an very important role to form the normal metallic YBCO thin film of the Josephson junction. All these facts are related with the S-N-S junctions.

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