| Project/Area Number |
09450141
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電子デバイス・機器工学
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| Research Institution | Shizuoka University |
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Principal Investigator |
MINAKTA Makoto Shizuoka University, Research Institute of Electronics, Professor, 電子工学研究所, 教授 (80174085)
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| Co-Investigator(Kenkyū-buntansha) |
NOMURA Takashi Shizuoka University, Research Institute of Electronics, Research Associate, 電子工学研究所, 助手 (90172816)
ISHIKAWA Kenji Shizuoka University, Research Institute of Electronics, Associate Professor, 電子工学研究所, 助教授 (50022140)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥5,600,000 (Direct Cost: ¥5,600,000)
Fiscal Year 1998: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1997: ¥3,300,000 (Direct Cost: ¥3,300,000)
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| Keywords | nanometer domain inversion / high densitiy memory / LiTaO_3 / LiNbO_3 / P-E hysteresis curve / threshold of domain nucleation / threshold of domain expansion / coherent detection / P-Eヒステリシスカープ / P-Eヒステリシスカーブ |
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| Research Abstract |
The crystal of ferroelectric materials such as LiNbO_3 and LiTaO_3 have large spontaneous polarization and 180ﾟ domain structure at room temperature. Development of new opto-electronic devices such as ultra high capacity memory would be possible by realization of the nanometer scale domain inversion.
In this study, basic research of the nanometer scale domain inversion by an irradiation of electron beam to LiTaO_3 single crystal. High capacity memory is also investigated as an application. An irradiation to the area of smaller than 2 mum square by modified electron beam patterning equipment produces an inversion domain as large as 140 mumphi. Theoretical analysis reveal (1) an effect of coulomb Interaction is very strong, and charge distribution is estimated to be a trigonal pyramid with constant vertical angle, named as "sand glass" model. (2) There are two kinds of threshold value, the threshold of domain nucleation and the threshold of domain expansion. We have succeeded to form an inversion domain as small as 670 nm phi in the crystal of 500mum thick. A new method for imaging the inversion domains, named coherent detection, is also proposed based on the piezoelectric effect. Non-destructive and direct observation of the domains is achieved. A measurement of P-E hysteresis curve reveals (1) Ps is as large as *51muC/cm^2, and the curve is ideal square shape. (2) The threshold values are 204kV/cm and 120kV/cm for threshold of domain nucleation and threshold of domain expansion, respectively. Therefore domain inversion of LiTaO_3 single crystal is suitable for memory application. The results shown above would be informative for establishing the nanometer scale domain inversion technique and the device application.
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