Substrate temperature and laser fluence effects on properties of ZnO thin films deposited by pulsed laser deposition

The influence of substrate temperature and laser fluence on the optical, structure, surface topography/chemical composition of ZnO thin film have been studied by means of UV-Vis optical absorption, X-ray diffraction XRD, atomic force microscope AFM and X-ray photoelectrons spectroscopy XPS. The UV-Vis absorption spectra showed an absorption band around 350 nm due to ZnO nanostructure, and red shift in wavelength was observed at higher substrate temperature. XRD pattern revealed the poly-crystalline wurtzite structure of ZnO thin film deposited at 25 degrees C, that evolves into crystal phase (002) and (103) as substrate temperature increased irrespective of laser fluence, the average particle size is in range of 5-10 nm. The AFM 3D images showed that, the ZnO surface morphology becomes more smoother as the substrate temperature increases from 25 to 450 degrees C, irrespective of laser fluences. The XPS results reveal that Zn component increases with the substrate temperature, meanwhile the O component decreases leads improved improved stoichiometric properties of ZnO thin film.