Gas sensor

Abstract

According to one embodiment, a gas sensor includes a fixed electrode, and a film structure which covers the fixed electrode, forms a cavity inside the film structure, and includes a sensitive layer formed of an amorphous material containing a metal element, and a cap layer provided on the sensitive layer. The film structure is allowed to be deformed when the sensitive layer absorbs a predetermined gas.

What is claimed is: 
     
         1 . A gas sensor comprising:
 a fixed electrode; and   a film structure which covers the fixed electrode, forms a cavity inside the film structure, and includes:
 a sensitive layer formed of an amorphous material containing a metal element; and 
 a cap layer provided on the sensitive layer, 
   the film structure allowed to be deformed when the sensitive layer absorbs a predetermined gas.   
     
     
         2 . The gas sensor of  claim 1 , wherein
 the film structure further includes a base layer, and an intermediate layer provided between the sensitive layer and the base layer.   
     
     
         3 . The gas sensor of  claim 1 , further comprising a movable electrode provided with the film structure and facing the fixed electrode, wherein
 a shape or a position of the movable electrode is allowed to be changed in accordance with deformation of the film structure.   
     
     
         4 . The gas sensor of  claim 1 , wherein
 the sensitive layer functions as a movable electrode facing the fixed electrode.   
     
     
         5 . The gas sensor of  claim 1 , wherein
 the cap layer contains an element which brings about catalysis to dissociate a hydrogen molecule into hydrogen atoms.   
     
     
         6 . The gas sensor of  claim 1 , wherein
 the cap layer contains an element contained in the sensitive layer.   
     
     
         7 . The gas sensor of  claim 1 , wherein
 the cap layer contains at least one element selected from palladium (Pd), platinum (Pt), gold (Au), silicon (Si), phosphorous (P) and boron (B).   
     
     
         8 . The gas sensor of  claim 1 , wherein
 the amorphous material is a metallic glass material.   
     
     
         9 . The gas sensor of  claim 1 , wherein
 the amorphous material contains an element which brings about catalysis to dissociate a hydrogen molecule into hydrogen atoms.   
     
     
         10 . The gas sensor of  claim 1 , wherein
 the amorphous material contains at least one element selected from palladium (Pd), platinum (Pt) and gold (Au), and at least one element selected from silicon (Si), phosphorous (P) and boron (B).   
     
     
         11 . A gas sensor comprising a film structure, the film structure including:
 a sensitive layer formed of an amorphous material containing a metal element; and   a cap layer provided on the sensitive layer and containing at least one element selected from silicon (Si), phosphorous (P) and boron (B).   
     
     
         12 . The gas sensor of  claim 11 , wherein
 the amorphous material is a metallic glass material.   
     
     
         13 . The gas sensor of  claim 11 , wherein
 the amorphous material contains an element which brings about catalysis to dissociate a hydrogen molecule into hydrogen atoms.   
     
     
         14 . The gas sensor of  claim 11 , wherein
 the amorphous material contains at least one element selected from palladium (Pd), platinum (Pt) and gold (Au), and at least one element selected from silicon (Si), phosphorous (P) and boron (B).   
     
     
         15 . A gas sensor comprising a film structure, the film structure including:
 a base layer;   an intermediate layer provided on the base layer and containing at least one of titanium (Ti) and tantalum (Ta); and   a sensitive layer provided on the intermediate layer and formed of an amorphous material containing a metal element.   
     
     
         16 . The gas sensor of  claim 15 , wherein
 the intermediate layer further contains nitrogen (N).   
     
     
         17 . The gas sensor of  claim 15 , wherein
 the film structure further includes a cap layer provided on the sensitive layer.   
     
     
         18 . The gas sensor of  claim 15 , wherein
 the amorphous material is a metallic glass material.   
     
     
         19 . The gas sensor of  claim 15 , wherein
 the amorphous material contains an element which brings about catalysis to dissociate a hydrogen molecule into hydrogen atoms.   
     
     
         20 . The gas sensor of  claim 15 , wherein
 the amorphous material contains at least one element selected from palladium (Pd), platinum (Pt) and gold (Au), and at least one element selected from silicon (Si), phosphorous (P) and boron (B).