JPS5670448A - Oxygen sensor - Google Patents

Abstract

PURPOSE: To enable optional selection of the partial pressure of oxygen causing the change in current by using an electrode having a nonohmic barrier such as schottky barrier and the gas-transmitting property as an electrode on one side at least.

CONSTITUTION: On a substrate 1 made of insulating ceramics such as glass are formed one electrode 2 formed of a thin metal film and the like, a semiconductor oxide layer 3 of N type and the other gas-transmitting electrode 4 for forming the nonohmic barrier against the semiconductor layer 3. As this electrode 4, a thin film fitted by plasma flame spraying or, as an ultraparticulate film, fitted under the reduced pressure of about 10Torr of inactive gas or oxygen is desirable for making the film transmissible for gas. When a fixed voltage is given between both electrodes, sharp increase in current is caused at the place where the partial pressure of oxygen, i.e. A/F is near 18. Due to the carrier density near the surface of the semiconductor layer 3, the point where the current increases sharply changes and thus the setting at an optional A/F value becomes possible.

COPYRIGHT: (C)1981,JPO&Japio