Low-temperature Preparation and Evaluation of Ferroelectric Thin Films for FeRAM by Chemical Solution Process
| Project/Area Number |
11650702
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | Shonan Institute of Technology |
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Principal Investigator |
HAYASHI Takashi Shonan Institute of Tech., Prof.Mat.Sci. & Ceram.Tech, 工学部, 教授 (70023265)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | Chemical Process / FeRAM / SrBi_2Ta_2O_9 / Thin Films / Excimer UV / Spin-Coating / Metal Alkoxide / 化学溶液法 / 強誘電性 / ビスマス層状化合物 / 低温プロセシング / エキシマレーザー / ゾル・ゲル法 / ビスマス系 / ゾル・ゲル |
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| Research Abstract |
Recently, Bi-layered perovskite thin films such as Bi_4Ti_3O_<12>, SrBi_2Ta_2O_9 and SrBi_2Nb_2O_9 have been attracting much attention for use in nonvolatile random access memory (NvRAM) devices. Among them, SrBi_2Ta_2O_9 (SBT) thin films have an especially high potential for NvRAM applications, because SBT has superior fatigue-free properties and small coercive fields, Ec. SBT thin films have been fabricated predominantly by Sol-Gel method with metal alkoxides. It is very important to control the structure and crystallinity of SBT thin films in order to obtain the excellent ferroelectric properties. Low-temperature preparation of SBT thin films is desired for the application to silicon device. In this work, we focussed on the preparation and properties of SBT thin films using Excimer UV irradiation. Thin films of SBT gels were prepared on Pi (200nm)/Ti (50nm)/SiO_2/Si substrates by a spin-coating technique from alkoxide solutions of SBT precursors. The gel thin films were irradiated using Xe excimer UV lamp at various temperatures for 5min. The UV-processed films were calcined at 500℃ for 30min, and then annealed at 750℃ for 1h in an O_2 atmosphere. The SBT thin films exhibited random orientation with strong (115) orientation. The microstructure of the films consisted of fine grains of 0.1〜0.2μm. Strong IR absorption assigned to C-H group was observed in SBT gel films with Excimer UV irradiation in N_2 atmosphere, in contrast with the irradiation in O_2 atmosphere. The crystallinity of the prepared films was improved by the UV irradiation at 200℃. SBT thin films showed well-saturated P-E hysteresis curve with a remanent polarization of 4.1μC/cm^2 and coercive field of 88.7kV/cm. SBT thin films showed a dense microstructure with grain sizes of 500〜600nm
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Report
(3 results)
Research Products
(21 results)
