| 摘要 |
PURPOSE:To obtain a metallic oxide semiconductor which can be worked into a minute shape by forming a metallic film on a substrate, reacting the film with dilute nitric acid to obtain a reaction product, and forming a metallic film by thermal decomposition of the product. CONSTITUTION:A thin Sn film 2, for example, is formed on a ceramic or glassy substrate 1 by vapor deposition, sputtering etc. The film is dipped in a 0.1- 5vol% aq.soln. of nitric acid, and a film 2' of a white linear reaction product obtained by the reaction of Sn with nitric acid is formed in 0.5-10min. Then the film is placed in an electric furnace and heated at 400-600 deg.C for 1-10min, and an SnO2 film 2'' is deposited. In this way, a gas detecting film having a minute structure is formed. Besides Sn, Al can also be applied as the metallic film, and a treatment stage for depositing Pt and Pd on the metallic film may be added.
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