Fabrication parameters of ZnO jet nebulizer sprayed films: an analysis of morphological, optical and crystalline properties

Abstract

This study examines the influence of fabrication parameters on the morphological, optical, and structural characteristics of zinc oxide (ZnO) films prepared using the jet nebulizer spray pyrolysis technique. Specifically, we analyze the impact of the application distance (ranging from 2 to 8 cm), substrate temperature (ranging from 325 to 425 °C), carrier air pressure (ranging from 5 to 15 psi), and the molar percentage of deionized water/ethanol in the precursor solution (ranging from 0 to 25%). Scanning electron microscopy, X-ray diffraction, and optical transmittance spectroscopy are employed for characterization. Under the employed conditions, film thicknesses ranging between 100 and 680 nm, predominantly strong orientation along the 002 crystalline plane, and visible transparency between 70 and 90% are obtained. Additionally, various morphologies are identified and inspected. Particularly, films produced at longer distances, higher temperatures, and using low or moderate water/ethanol ratios exhibit higher visible transparency (90%), a homogeneous morphology devoid of grain overgrowth, and thicknesses up to 200 nm. These features are desirable for photonic and optoelectronic applications, thus motivating further investigations using the employed technique to obtain wider thicknesses while maintaining these target properties. In summary, this work evaluates the feasibility and tunability of producing transparent and homogeneous ZnO films using the low-cost jet nebulizer spray pyrolysis and contributes to the understanding of this growth process.