In this study, Al2O3 thin films of different thicknesses (50 nm, 100 nm, 150 nm, 200 nm, and 250 nm) were, first, grown using RF magnetron sputtering technique on glass substrate at 30 degrees C temperature, with 120 W power value. Then 250 nm ZnO was grown on these thin films. Microstructural analyses of the thin films were made by scanning electron microscope (SEM). It was observed that the particle size changed with increasing thickness of Al2O3 thin films. ZnO layer was grown onto alumina grown tubes with an approximate thickness of 250 nm. The grain morphology of ZnO was similar to alumina, about 25-30 nm grain size. Energy-dispersive X-ray analysis (EDX) detector was used to determine the chemical composition of the samples. These results have indicated that ZnO thin films are successfully formed on alumina tubes. Crystal structure analyses of all samples were examined using the X-ray diffraction (XRD) technique. In addition, the optical properties of the samples were examined with ultraviolet-visible-near infrared spectrometer (UV-VIS-NIR). This work provides valuable references for the application of Al2O3 as insulating buffer layers.