Characterization and Control of Nanostructure Size Variation

Abstract

Results from the characterization of the size variation of nanostructures in a series of thin films prepared by varying a component fraction in the precursor solution are reported and discussed in terms of the physics and chemistry behind the variation. Changes in the refractive index and thickness upon vapor adsorption were used to calculate the adsorbed volume as a function of vapor pressure and then analyzed to obtain size, size variation, and total volume of nanostructures in the films. With an increasing amount of dimethyldiethoxysilane (DMDEOS) in precursor solution, the condensation polymerization reaction proceeded to decrease the silanol group concentration, increasing the ≡Si–O–Si≡ network connectivity number (m) and Young's modulus (E) of the resultant film. With further increase of the DMDEOS concentration, the methyl group concentration in film was increased with decreasing m and E. It was demonstrated that the experimentally observed dependence of the nanostructure size variation reflects the physics and chemistry behind the preparation processes, and provides a good insight into a strategy for minimizing the variability.