Highly c -Axis Oriented ZnO Thin Films on Glass Substrate by Pulsed Laser Deposition: Fluence-Dependent Effects

Abstract

Highly c-axis oriented crystalline ZnO thin films were deposited onto glass substrates by the pulsedlaser deposition technique employing a Nd:YAG laser via its second harmonic, and different fluence(0.4 3.2 J/cm2) focused on ceramic targets. The influence of the laser fluence on the structure, surface morphology, and optical properties of ZnO films was characterized by X-ray diffraction and Raman spectroscopy, scanning electron microscopy, and transmission UV-IR spectra, respectively. Above the ablation threshold, the laser fluence used is directly linked to the structural defects in the film, thus allowing easy control of the intrinsic stress in the film. Micro-Raman spectra presented vibrational modes, which are assigned to surface phonons modes, indicating the preponderance of nanostructures effects on the films. Our results indicate that the experimental arrangement developed allows the suppression of the superheating effect of the melted target material in the case of visible wavelength lasers irradiations, obtaining films of comparable quality to those obtained by UV-lasers