A LOW-TEMPERATURE OXYGEN SENSOR BASED ON THE SI/LAF3/PT CAPACITIVE STRUCTURE

A new Si/LaF3/Pt oxygen-sensitive structure working on the basis of the field effect in silicon has been developed. It meets the demands of semiconductor technology and is convenient for detecting oxygen both in gas mixtures and in liquids. A low 90% response time of 90 s and a Nernstian sensitivity of 59 mV/lg p(O2) are obtained. The sensor is shown to be able to detect oxygen partial pressures within a range of eight orders of magnitude. A comparison between the Si/LaF3/Pt and Si/SiO2/Si3N4/Pt structures has been carried out in order to consider whether LaF3 is involved in the oxygen-sensing mechanism. The parameters of the platinum layer are changed in order to improve the sensor function. XPS measurements are used to explain the influence of the treatment of LaF3 with solutions varying in pH.