Doping induced structural and compositional changes in ZnO spray pyrolysed films and the effects on optical and electrical properties

Highly transparent, conductive ZnO films have been deposited by spray pyrolysis of a zinc acetate based solution. Quality films are yielded as our process is analogous to an aerosol assisted chemical vapour deposition rather than a droplet deposition spray pyrolysis technique. The properties of the films are governed by the additives to the base precursor solution. When aluminium acetylacetonate is added to the precursor solution, ZnO:Al films are grown with free charge carrier concentrations of more than 1020 cm−3. The carrier density and mobility are measured by both Hall probe and near infrared spectroscopy. Film growth and grain size, morphology and orientation are altered using an increased percentage of ZnCl2 in the precursor, which results in a 10 fold increase in charge carrier mobility. An investigation is presented correlating the composition of the precursor solution with the chemical, structural, electrical and optical properties of the grown films.