| Project/Area Number |
15360157
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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 |
Electronic materials/Electric materials
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| Research Institution | Tokyo Institute of Technology (2004-2005)
Tohoku University (2003) |
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Principal Investigator |
TOKUMITSU Eisuke Tokyo Institute of Technology, Precision & Intelligence Laboratory, Associate Professor, 精密工学研究所, 助教授 (10197882)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥15,000,000 (Direct Cost: ¥15,000,000)
Fiscal Year 2005: ¥5,100,000 (Direct Cost: ¥5,100,000)
Fiscal Year 2004: ¥5,700,000 (Direct Cost: ¥5,700,000)
Fiscal Year 2003: ¥4,200,000 (Direct Cost: ¥4,200,000)
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| Keywords | ferroelectric material / field-effect transistor (FET) / gate insulator / conductive oxide / on-current / MOSFET / (Bi,La)_4Ti_3O_<12> / 電界効果型トランジスタ(FET) / チタンジルコン酸鉛 / チタン酸ランタンビスマス(BLT) / チタンジルコン酸鉛(PZT) |
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| Research Abstract |
The objective of this research project is to realize new switching device using ferroelectric materials which can control huge charge density of 10-50 μC/cm^2. In this work, we used indium-tin-oxide (ITO) as a channel material instead of Si with ferroelectric gate insulator. First, we fabricated and characterized ferroelectric thin films, Pb(Zr,Ti)O_3 (PZT) and (Bi,La)_4Ti_3O_<12> (BLT), and ITO thin films. Next, we fabricated ferroelectric-gate thin film transistors (TFTs) using ITO/PZT and ITO/BLT structures. Drain current - drain voltage characteristics shows normal n-channel transistor operation with clear drain current saturation. In particular, a large on-current of 0.1 mA/μm was obtained for ITO/BLT TFTs with a channel length of 5 μm. This value is as large as the on-current of Si-MOSFET with same channel length. From this on-current, the charge density. used in the fabricated device is as large 20 μC/cm^2, which proved the operation principle proposed in this work. Furthermore, we examined the details of device parameter dependence of the electrical properties. We also demonstrated that the off-current of the device can be drastically reduced by mechanically polishing the surface of the ferroelectric film. The ITIO/BLT structure ferroelectric-gate TFT with an on-current of 10^<-3> A and an off-current of 10^<-11> A (on/off ratio is more than 10^7) was demonstrated. In addition, transparent ferroelectric-gate TFTs were also demonstrated on quartz substrates.
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