Humidity sensing properties of Ce-doped nanoporous ZnO thin film prepared by sol-gel method

The humidity sensitive characteristics of the sensor fabricated from Ce-doped nanoporous ZnO by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes were investigated at different sintering temperatures. The nanoporous thin films were prepared by sol-gel technique. It was found that the impedance of the sensor sintered at 600 °C changed more than four order of magnitude in the relative humidity (RH) range of 11%–95% at 25 °C. The response and recovery time of the sensor were about 13 and 17 s, respectively. The sensor showed high humidity sensitivity, rapid response and recovery, prominent stability, good repeatability and narrow hysteresis loop. These results indicated that Ce-doped nanoporous ZnO thin films can be used in fabricating high-performance humidity sensors.