A new technique for the preparation of highly sensitive hydrogen sensors based on SnO2(Bi2O3) thin films

✍ Scribed by Giorgio Sberveglieri; Silvio Groppelli; Paolo Nelli; Alberto Camanzi

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 456 KB
• Volume: 5
• Category: Article
• ISSN: 0925-4005
• DOI: 10.1016/0925-4005(91)80258-l

✦ Synopsis

H, in air can be detected with sensors based on semiconductor oxides. A new technique for growing a hydrogen sensor based on SnO,(Bi,O,) thin films is presented here. The thin films have a thickness of 200-250 nm and the metals are in the atomic ratio Bi/Sn.= (3-S) at.%](97-95) at.%. The two metals are deposited by means of evaporation in a high vacuum; the metal-semiconductor phase transformation consists of a thermal cycle in air. The initial step involves a fast transition from room temperature up to 350 "C over a few minutes, and causes a local partial melting of the metallic alloy. The surface of these thin films is made up of spongy agglomerates, having a surface area about 1000 times larger than a flat surface and covering about 60-70% of the total area. Sensors grown with this method also seem to be able to detect a few ppm of H, in air at 450 "C with a response time of about IO-20 s.