| Project/Area Number |
08455301
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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 |
Inorganic materials/Physical properties
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| Research Institution | Gifu University |
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Principal Investigator |
TAKAHASHI Yasutaka Gifu University, Faculty of Engineering, Professor, 工学部, 教授 (00023177)
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| Co-Investigator(Kenkyū-buntansha) |
BAN Takayuki Gifu University, Faculty of Engineering, Assistant Professor, 工学部, 助手 (70273125)
OHYA Yutaka Gifu University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (80167311)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 1997: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1996: ¥6,400,000 (Direct Cost: ¥6,400,000)
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| Keywords | Sol-gel method / Ethanolamine method / Effect of compiling thin layrs / ITO thin films / Doping effect of divalent metal ions / Transparent electrically conducting films / Moisture sensor / 湿度センサ / 透明導電薄膜 |
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| Research Abstract |
Both an organic sol system derived from indium acetate and aqueous sol system consisted of indium hydroxide were investigated. The results obtained through the investigation are summarized as follows :
(1) The organic sol system affords more densified, very transparent ITO films with high conductivities of 2500 to 3000 S/cm by firing the gel films at 600 to 650ﾟC followed by post annealing in vacuo. But indium alkoxide is unsuitable as the starting material, probably due to impurities included in it.
(2) The conductivity is mainly controlled by the carrier mobility, and the mobility can be increased with increase in crystallite size.
(3) Piling of thin layrs of about 20 nm in thickness is more useful to enhance the crystallite size than the single coating of a thick film. The multicoated films have a typical columnar texture, indicative of the importance of homo-epitaxial effect for crystal growth.
(4) By doping indium oxide with a divalent metal ion, the resistivities can be increased as expected, and the resitivities can be controlled by selecting the kind and concentration of the dopant.
(5) These films with higher resistivities have the fundamental characteristics as a moisture sensor, and the response is very high, rapid and selective ; it is almost independent of the presence of other reducing gases in the atmosphere. This property may be attributed to a mechanism related to adsorption of water gas onto the surface of the doped indium oxide films.
(6) The films obtained from aquenous sols have lower density and large porosity. Therefore, those films have lower conductivities, and excellent properties for moisture-sensing.
(7) Other n-type oxide semiconductors such as tin dioxide and zinc oxide were found to have a moisture-sensing property very similar to that of indium oxide and to be useful as the basic materials of moisture sensors.
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