SILAR-coated Mg-doped ZnO thin films for ammonia vapor sensing applications

Abstract

Ammonia serves an important role in medical diagnosis and food processing technology. Development of sensors at lower operating temperatures has gathered momentum for the detection and monitoring of ammonia vapor in the recent years. In this work, magnesium-doped zinc oxide thin films were prepared by successive ionic layer adsorption and reaction process and their room temperature ethanol sensing properties were analyzed. The films have been investigated for their structures, morphological, optical, and gas sensing properties. The findings of X-ray diffraction show that the films have polycrystalline nature with a Wurtzite structure. The magnesium doping reduces the size of the crystallites. Scanning electron microscope images show that high doping concentration changes the shape of the grains from spherical to nanoflowers. The optical transmission increases and bandgap also increase from 3.03 to 3.17 eV as the doping concentration of magnesium increases from 0 to 5 wt%. Role of ZnO nanoflowers at room temperature operation coordination with a highly sensitive response and recovery times (13 and 20 s) with the low deposition cost suggests suitability for developing a low-power cost-effective ammonia vapor sensor.