The effect of ultrasonic wave amplitude on the physical properties of zinc oxide (ZnO) deposited by ultrasonic spray method

In this study, high quality zinc oxide (ZnO) thin films, with improved properties, were prepared by a costeffective ultrasonic spray pyrolysis technique via a careful optimization of the used ultrasonic wave amplitude. The deposition process was performed on glass substrate and were subsequently annealed at 400 degrees C. We investigated the effect of various ultrasonic wave amplitude on the structural, surface morphology, optical and electrical properties of the obtained thin films, after varying the applied wave amplitude. Furthermore, deposited thin films were studied by means of XRD, UV-vis spectrophotometer, scanning electron microscope, and four point probe technique. XRD analysis confirmed that obtained ZnO thin films have polycrystalline structure and a wurtzite (hexagonal) phase, with a c-axis preferred orientation (002). The crystallite size was about 23-30 nm. The SEM micrographs of the surface morphology show uniform, homogenous and dense films with granular structures. The films thicknesses were found to be dependent on the used wave amplitude; they were ranged from 184 to 423.5 nm. In addition, the optical properties of the deposited thin films reveal that the films are highly transparent in the visible region above 80%, while the value of energy band gap varies from 3.24 to 3.27 eV. The Electrical properties investigation revealed a resistivity around 10(-3) Omega.cm, showing also a non negligible dependency with the wave amplitude tuning. We obtained an improvement in the carrier concentration (1.6 x 10(20)-3.9 x 10(20) cm(-3)) and mobility (4.2-15 cm(2)/V.s) with the ultrasonic wave amplitude rising. High quality ZnO thin films with enhanced properties are in demand and have a large wide of applications in optoelectronics and solar cells.

Automated summary

In this study, high quality ZnO thin films were prepared by an ultrasonic spray pyrolysis technique with careful optimization of the ultrasonic wave amplitude. The films exhibited polycrystalline structure with a wurtzite phase, and their thickness and optical properties were influenced by the applied wave amplitude. Various techniques such as XRD and SEM were used to characterize the thin films, confirming their improved properties with increasing ultrasonic wave amplitude.