Pulsed laser deposition of plasmonic structures in air by irradiation through the substrate

This work presents results from a method for single step fabrication of noble metal nanostructures in air that express plasmonic properties. A special configuration of the laser irradiation through the substrate is applied. Due to the interaction of the deposited material with the incident laser radiation, the resulting structure could be a dense nanoparticle monolayer instead of three-dimensional structure, which is usually obtained at pulsed laser deposition in air. The proposed geometry of irradiation is characterized by several key parameters that are defined and their influence on the properties of the fabricated structures is studied. The change of the processing conditions may result in significant change of the optical properties of the deposited structures. This effect is more expressed in the case of silver. The deposition of gold at the presented method leads to a saturation of the amount of the deposited material, and respectively to constant optical properties with the increase of the deposition time at fixed other parameters. Conditions where formation of a monolayer of well-defined separated nanoparticles are also presented. It is demonstrated that using this method composite gold/silver structures with tunable optical properties can be obtained. On a basis of numerical calculations, the optical properties of the obtained structure and the temperature evolution of the formed material are obtained. These data are used to explain the observed dependences and the formation mechanism. The method is simple and can be applied for efficient deposition of plasmonic systems with potential application in the design of different optical and sensor elements.