Fluorine doped ZnO thin film as acetaldehyde sensor

Trace level detection of acetaldehyde vapour in a real time environment is highly essential, since it causes various illnesses and disorders once it exceeds the human permissible limit. Additionally, acetaldehyde is one of the predominant markers of fruit and vegetable spoilage levels. Therefore it is vital to develop relatively low cost, highly selective and room temperature operating acetaldehyde sensors. In this regard, we have fabricated a room temperature acetaldehyde sensor using fluorine-doped ZnO nanostructured thin film. Further, the investigations were carried out to study the influence of fluorine doping on the structural, morphological, optical, electrical and room temperature vapour sensing characteristics of ZnO thin film. Structural analysis revealed the formation of a hexagonal wurtzite structure for all the undoped and fluorine-doped ZnO samples. Average crystallite size and micro-strain were decreased and increased respectively with an increase in fluorine-dopant concentration. The film deposited with 4 wt.% fluorine-dopant concentration was found to be highly selective towards 100 ppm of acetaldehyde with a maximum response of 4.8 at room temperature. Response and recovery times were observed to be 18 and 25 s respectively towards 100 ppm of acetaldehyde.