Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Responsive to non-optical – non-electrical signal
Reexamination Certificate
2007-10-02
2007-10-02
Cygan, Michael (Department: 2855)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Responsive to non-optical, non-electrical signal
C073S031060
Reexamination Certificate
active
11358621
ABSTRACT:
The present invention provides a gas sensor having excellent humidity resistance even if used in a high temperature and high humidity atmosphere. According to the present invention, a gas sensor is comprised of: a silicon substrate; a metal-oxide semiconductor portion comprised mainly of SnO2and formed on the substrate; and a catalytic portion comprised of Pd and dispersed on a surface of the metal-oxide semiconductor portion, wherein the metal-oxide semiconductor portion and the catalytic portion constitute a gas sensing portion. Furthermore, an insulating portion comprised mainly of SiO2is formed dispersedly on a surface of the gas sensing portion. Further, the catalytic portion and the insulating portion are formed on the surface of the metal-oxide semiconductor portion so that the surface additive rate, which is expressed by Si/(Pd+Si) representing the ratio in the number of atoms of Si to Pd, of the gas sensing portion having the insulating portion may be 65% or more to 97% or less, and so that the surface additive rate, which is expressed by Si/(Sn+Si) representing the ratio in the number of atoms of Si to Sn, of the gas sensing portion may be 75% or more to 97% or less.
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Kida Masahito
Kojima Takio
Nakagawa Shin-ichi
Nakano Yoshihiro
Cygan Michael
Kusner & Jaffe
NGK Spark Plug Co. Ltd.
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