The influence of atomic layer deposition process temperature on ZnO thin film structure

Abstract The comprehensive investigation results of the influence of ZnO thin films deposition parameters on their structure, mechanical and optical properties are presented in the paper. Zinc oxide layers were prepared using atomic layer deposition (ALD) method. For the evaluation of morphology and structure of the ZnO films, both scanning and transmission electron microscopy was used. Transparency test was carried out using UV/VIS spectroscopy. The atomic concentration of the particular elements of ZnO layer was calculated from the XPS measurements. Chemical analysis was extended to measurements of micro and nanostructure of ZnO layer with the use of TOF-SIMS spectrometry. The Oliver-Pharr method was used to measure the instrumental hardness, while the scratch test was performed to study the layers adhesion to the surface. The uniform structure of the investigated coatings without any visible delamination was observed. Despite the very low thickness, the layers demonstrated a good adhesion to the substrate. The results showed that the temperature of ALD process significantly affects the structure and transparency of ZnO thin films. The number of ALD cycles is also crucial regarding transparency.