Nanoprocessing of silicon substrate using surface plasmon polaritons of gold particle and polystyrene particle excited by femtosecond laser

Abstract

Nanohole processing of silicon substrate using surface plasmon polaritons of nano gold excited by femtosecond laser is described in comparison with the nanohole processing with transparent polystyrene (PS) nanoparticle template. Gold particles with diameters of 40, 80, or 200 nm are spin coated on the substrate, and a 100 fs, 820 nm laser pulse is used to irradiate the samples. The produced holes are analyzed by scanning electron microscopy and atomic force microscopy. A theoretical analysis of the experimental results is conducted by FDTD (Finite Difference Time Domain) simulation. The dependence of the laser fluence and particle size on the nanohole properties is studied. The nanohole profiles correspond to the field distributions on the Si substrate at low fluence region. A highest electric field enhancement factor of about 26 is obtained for gold particles with a diameter of 200 nm.