Laser nanostructuring for plasmon enhancement of Ag/ZnO optical characteristics

Abstract

The experimental and theoretical investigations of the optical characteristics of laser nanostructured Ag nanoparticles (AgNPs) in ZnO medium are of particular interest for this study. The Ag-ZnO nanocomposites are fabricated by room temperature pulsed laser synthesis method. Ag nanoparticles are prepared by laser deposition and subsequent laser annealing of silver thin film. Laser annealing of silver layer is performed at second and third harmonics of the Nd:YAG laser. The morphology of AgNPs differs significantly after the UV and VIS surface modification. The morphology and optical properties of the samples are studied according to the annealing regimes. A comparative study of the measured plasmon resonance properties with the theoretical calculations of the extinction efficiency by generalized multiparticle Mie (GMM) method is carried out. The extinction spectrum is determined as a function of the nanoparticles size distribution and the surrounding ZnO medium. The electromagnetic field intensity enhancement realized in the “hot spots” of AgNPs leads to substantial enhancement of the near band-edge UV photoluminescence (PL) emission of ZnO nanostructures and attenuation of the defect-related deep-level VIS PL signal after annealing at 355 nm and 532 nm.