Micro humidity sensors based on ZnO–In2O3 thin films with high performances

Micro humidity sensors are fabricated by radio-frequency sputtering ZnO and In2O3 thin films on SiO2/Si substrates with interdigitated Pt signal electrodes. By adjusting the sensing film form, the micro sensors with a tiny area (1.36mm×0.55mm) exhibit controllable humidity sensing properties. The be...

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Bibliographic Details
Published in:Sensors and actuators. B, Chemical Chemical, 2012-04, Vol.165 (1), p.76-81
Main Authors: Liang, Qingcheng, Xu, Hongliang, Zhao, Jianxun, Gao, Shang
Format: Article
Language:English
Subjects:
electrodes
impedance
In2O3
Metal oxide semiconductors
Micro sensors
Radio-frequency sputtering
relative humidity
zinc oxide
ZnO
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Summary:Micro humidity sensors are fabricated by radio-frequency sputtering ZnO and In2O3 thin films on SiO2/Si substrates with interdigitated Pt signal electrodes. By adjusting the sensing film form, the micro sensors with a tiny area (1.36mm×0.55mm) exhibit controllable humidity sensing properties. The best sample is obtained by sputtering two times of ZnO and one time of In2O3 on sensor active area (0.63mm×0.55mm). The corresponding impedance changes by more than four orders of magnitude over the whole testing humidity range (from 11% to 95% relative humidity), and the response and recovery times are about 15s and 40s, respectively. High stability and good consistency are also observed based on the as-fabricated sensors. The improved and excellent humidity sensing properties are explained by the hetero junctions between ZnO and In2O3 thin films. High sensor performance and large-scale fabricating potentiality demonstrate that the micro humidity sensors are very promising devices for humidity detection which could be produced at industrial level.
ISSN:0925-4005
1873-3077
DOI:10.1016/j.snb.2012.02.019