Tailoring the properties of zinc oxide films by incorporating gold nanoparticles using RF magnetron sputtering

Abstract

Nanoscale noble metal-incorporated ZnO nanostructures can have potential applications in developing chemical and biological sensors, optical filters, ultrafast switching devices, etc. The structural, morphological and optical properties of the as-deposited pure and Au-incorporated RF-sputtered ZnO films were investigated. XRD analysis suggests that the presence of Au nanoparticles strongly promotes the growth of well-crystalline grains of ZnO along $$\left\langle {00{\text{1}}} \right\rangle$$ direction. Surface morphology examined using AFM and FESEM micrographs and compositional analysis using EDX spectra reveal that Au acts as a nucleating center for the growth of high-crystalline grains, leading to the formation of specific structures. The observed reduction in transmittance with Au incorporation concentration can be attributed to LSPR of gold nanoparticles, scattering, increased surface roughness and increased thicknesses of the films. Systematic increase in the intensity of the plasmonic peak along with a shift in its position towards longer wavelength region is observed with increase in Au incorporation concentration. The PL spectra of the films show a NBE emission due to excitonic transition in ZnO and blue emission originating from deep-level defects in ZnO. The influence of Au nanoparticles on the crystallization of ZnO grains, evolution of surface morphology of ZnO nanostructured films and modification in the UV emission efficiency of ZnO films due to SPR of Au nanoparticles are studied in detail.