Optical properties of nanostructured ruthenium dioxide thin films via sol–gel approach

Abstract

High purity ruthenium dioxide (RuO2) nanoparticles with the average size is about 9 nm in diameter are readily synthesized through a low cost sol–gel method. RuO2 thin films have been deposited on SiO2 substrates by sol–gel spin coating techniques at room temperature, followed by annealing at 500 °C for 2 h. The result of X-ray diffraction indicates that the RuO2 nanoparticles are well crystallized with a rutile tetragonal structure. Morphological of RuO2 films were characterized using atomic force microscopy (AFM), transmission electron microscopy and high resolution transmission electron microscopy. The AFM images confirmed a spherical-shape nanoparticles with diameter of 9 nm and surface roughness of 12 nm of the films. The optical absorption studies showed the presence of direct band transition with band gap equal to 1.87 eV. Refractive index and dielectric properties of the films were estimated from optical measurements. Room temperature photoluminescence of RuO2 film showed an emission band at 432 nm.