Effect of laser Fluence Energy on Morphological, Structural and Optical Properties of Gold and Silver Thin Films Prepared by Pulse Laser Deposition Method

Abstract

We report the growth and characterization of (Ag, Au) nanoparticles thin films deposition on a glass substrate by pulse laser deposition (PLD) method. The (Ag, Au) thin films prepared through different laser fluence (0.4, 0.6 and 0.7) J/cm2. The effect of laser fluence energy on the morphological, structural and optical properties were studied by XRD, AFM and UV-Visible spectrophotometer. X-ray diffraction showed nanostructure, with dominated peak at 2θ values 38.3182° corresponding to (111) for silver and peak observed at 2θ values 38.2° which can be indexed to the (111) of face-centered cubic (fcc) structure for Au. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with grain sizes ranging from 21.81 to 37.06 nm for Ag, and grain sizes ranging from 12.63 to 15.01nm for Au thin films. The results showed the Average gran Size increased with increasing laser fluence energy and RMS roughness increased with increasing laser fluence energy. Optical properties measurements showed that(Ag, Au) thin films have two peak the first one related with interband transitions, and the second peak formation of a surface plasmon peak (SPR). Optical properties measurements showed transformation from metallic properties of bulk (Ag, Au) to semiconductor properties when formed by sort of nanostructure evidenced by the formation of optical energy gap about (0.8, 0.7 and 0.5) eV when laser fluence increased (0.4, 0.6 and 0.7) J/cm2 respectively for Ag thin films. when grain size become smaller the optical energy gap increased. Optical energy gap(Eg) decreased (1.4, 1.2 and 0.8) eV when laser fluence increased (0.4, 0.6 and 0.7) J/cm2 respectively for Au thin films.