Effect of Water Vapor and Surface Morphology on the Low Temperature Response of Metal Oxide Semiconductor Gas Sensors

Materials

Konrad Maier²  Andreas Helwig²  Gerhard Müller²  Pascal Hille¹  Martin Eickhoff¹ 

[1] I. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen 35392, Germany; E-Mails:;Airbus Group Innovations, München D-81663, Germany; E-Mails:

关键词: low temperature gas response;    integrator gas response;    SnO₂;    surface morphology;    water vapor;    BET adsorption;   

DOI  :  10.3390/ma8095323

来源: mdpi

【 摘 要 】

In this work the low temperature response of metal oxide semiconductor gas sensors is analyzed. Important characteristics of this low-temperature response are a pronounced selectivity to acid- and base-forming gases and a large disparity of response and recovery time constants which often leads to an integrator-type of gas response. We show that this kind of sensor performance is related to the trend of semiconductor gas sensors to adsorb water vapor in multi-layer form and that this ability is sensitively influenced by the surface morphology. In particular we show that surface roughness in the nanometer range enhances desorption of water from multi-layer adsorbates, enabling them to respond more swiftly to changes in the ambient humidity. Further experiments reveal that reactive gases, such as NO₂ and NH₃, which are easily absorbed in the water adsorbate layers, are more easily exchanged across the liquid/air interface when the humidity in the ambient air is high.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.