In this study we focused on the influence of the deposition process of ZnO thin film of ≈ 300 nm thickness, grown on glass and silicon substrates by atomic layer deposition (ALD) technique, on the morphology, optical properties, AC conductivity and dielectric properties. The atomic structure of the ZnO film was analyzed using scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDX) and incident X-ray diffraction pattern (XRD). The (XRD) pattern confirms the presence of crystalline phase which is clearly observed in the SEM image . The value of the crystallite size was found to be equal 35.41nm. Transparency study was performed by UV-VIS spectroscopy. A key element of this study was to prove that it is practically impossible to attribute the optical energy gap (Eg) and the refractive index (n) dependence to any typical thin film material because these parameters depend on the deposition condition and growth temperature. The values of the optical energy gap and the refractive index estimated from the absorption spectrum (Eg=3.32eV, n=2.29) was compared with that obtained from the transmittance and reflectance measurements (Eg=3.36 , n= 2.272). A new relations have been proposed on the basis of the best fit , for calculating the refractive index, have been determined and compared with the values estimated by different researchers showing an excellent agreement. The electrical parameters such as dielectric characteristics and the AC conductivity were also estimated at different temperatures ranging from (303 – 413 K) against the frequency ranging from (1 K Hz to 1 MH). The AC conductivity behavior was studied to explore the mechanism of conduction. Further analysis revealed that the corelated barrier hopping model (CBH), is the predominate theoretical model to elucidate the conduction mechanism existing in our ZnO thin film . This article contains recent advances in the modified ZnO metal oxide prepared by (ALD), for efficient approach for sensor device fabrication depending mainly on the estimated parameters. |
