ZnO thin film prepared by a sol-gel spin coating technique for NO2 detection

The ZnO thin film sensor is developed by a low-cost sol gel spin coating technique on a glass substrate. The structural, morphological, surface compositional, optical and electrical properties of the ZnO thin film were studied using XRD, FESEM, XPS, HRTEM, FTIR and UV VIS techniques. The gas sensing performance of ZnO thin film is studied at different operating temperature for various gases like NO2, NH3, CH3OH, Cl-2 and H2S. The ZnO thin film sensor was highly selective towards NO2 gas with a maximum response of 12.3 at 100 ppm concentration at 200 degrees C operating temperature. ZnO film sensor can also detect low concentration of NO2 gas up to 5 ppm with the response of 4.1. The ZnO thin film sensor shows excellent repeatability, high stability and moderate response and recovery time, for NO2 gas in the 5-100 ppm concentration range.