Novel Electrostatic Spray Deposition (ESD) Techniques for Growth Mechanisms of Solution-Dependent Zinc Oxide (ZnO) Thin Films

In this work, a systematic and easy approach to nanocrystalline (NC) ZnO thin films growth by employing the novel ESD technique at temperatures ranging from 300 °C to 500 °C have been studied. For the subsequent investigation, three sets of 20 ml spray solutions with a 0.1 M concentration of the ESD technique were generated within the laboratory facilities. The solutions contained 80% ethanol (CH3 CH2 OH) and 20% distilled water (H2 O). Zinc chloride (ZnCl2 ) was utilized as the zinc source for all the 20 ml solution. In order to address the fundamental causes of the microstructural changes, two sets of the spray solution were enhanced with hydrochloric acid (HCl) at concentrations of 0.005 M and 0.015 M, respectively. X-ray diffraction (XRD) depictions showed that the ZnO nanoparticles had a pristine wurtzite crystal structure. Energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) showed the composition ratio and growth confirmation of ZnO on the conductive In2O3:Sn (ITiO) coated alkali-free glass substrates. The results show that adding the maximum amount of HCl to the spray solution suppresses the c-axis crystal growth of ZnO thin films and enhance the a-axis (100) crystal growth. The adhesion of anions was believed to be responsible for this suppression. Microstructural parameters (MIP), specifically lattice parameters (a (Å), c (Å)), positional parameters (μ), bond lengths (L (Å)), full width at half maximum (FWHM), and average crystallite sizes (D (nm)), are examined. This finding signifies a pivotal advancement in cost-efficient industrial and commercial applications for ESD-deposited devices.