Re-activation of an all solid state oxygen sensor

The silicon based semiconductor structure Si/SiO2/Si3N4/LaF3/Pt can be used as a potentiometric oxygen sensor working at room temperature. A thermal r e-activation can be applied to overcome the earlier disadvantage of an incr ease in response time with continuous use. Using the Pt gate electrode as a resistive heater, very short electrical high-power pulses can be applied. A heating time as short as 300 ns was sufficient for the re-activation of t he sensor. This way, only the sensitive thin layer system LaF3/Pt was heate d, and the whole sensor was at room temperature immediately after heating. Impedance spectroscopy, X-ray photoelectron spectroscopy (XPS) and quadrupl e mass spectrometric (QMS)-thermogravimetry (TG) were used to investigate t he mechanism of deterioration in dynamic sensor behaviour and re-activation . The formation of hydrated carbonate and the desorption of CO2 and H2O hav e been shown to be the causes. (C) 2001 Elsevier Science B.V. All rights re served.