ORIGINAL PAPER Deposition of silica thin films formed by sol–gel method Hasan Guleryuz • Ingeborg Kaus • Claudine Filia`tre • Tor Grande • Mari-Ann Einarsrud Received: 24 September 2009 / Accepted: 2 March 2010 / Published online: 17 March 2010 Ó Springer Science+Business Media, LLC 2010 Abstract Deposition of silica thin films on silicon wafer was investigated by in situ mass measurements with a microbalance configured for dip coating. Mass change was recorded with respect to deposition time when the substrate was fully immersed in the silica sol. Mass gain during deposition was higher than predicted from monolayer coverage of silica nano particles. This implied that depo- sition was facilitated by gelling of the nanoparticles on the substrate. The rate of deposition was enhanced by increasing the particle concentration in the sol and by decreasing the particle size from 12 to 5 nm. Increasing the salt concentration of the silica sol at constant pH enhanced the deposition of the silica particles. Reducing the pH of the sol from 10 to 6 decreased the deposition rate due to aggregation of the primary silica particles. Keywords Silica Á Thin film Á Gravimetry Á Deposition kinetics Á Sol–gel 1 Introduction Many new technologies and state of the art devices are developed by the application of thin films to modify the properties of surfaces and interfaces. Improved performance and reliability of the products are strictly based on the properties of the thin films. Depending on the application, thin films can be produced by a number of coating methods based on different physical and chemical principles [1]. Main coating methods that are used for the production of thin films are based on vapour deposition, sputtering, evaporation and chemical solution deposition methods [2, 3]. Among these, the sol–gel method appears to be a convenient deposition method due to simple operation schemes, relatively low cost and environmental impact. Thin film formation by sol–gel method involves preparation of a sol, deposition of the sol onto a surface, formation of a gel state and drying of the gel. Depending on the sol parameters and deposition conditions, structure of the gel and drying regime may vary. All of the three stages are interrelated and determine the final structure of the thin film [2, 3]. Thin films produced by the sol gel method are deposited from aqueous or non aqueous solutions containing precur- sors incorporated in a solvent. These precursors are capable of forming a sol containing nanoparticles which form a gel state as a result of the surface interactions. Variations in the particle concentration change the frequency of interactions while particle size, concentration of ions and pH alter the physicochemical nature of the surfaces. Hence, surface interactions are strongly influenced by the sol chemistry [2, 4–8]. The particles that are moving in the sol as a result of Brownian diffusion and hydrodynamic forces experience random collisions. The conditions promoting the frequency of collisions and interaction efficiencies lead to formation of small clusters and aggregates which grow in size at a certain rate. Individually growing aggregates will finally interact and a gel structure containing solid and liquid phases will form [2, 8]. Growth of a thin film on a substrate is sustained by irreversible deposition of the particles in the gel structure. H. Guleryuz Á T. Grande Á M.-A. Einarsrud (&) Department of Materials Science and Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway e-mail: mari-ann.einarsrud@material.ntnu.no I. Kaus SINTEF Materials and Chemistry, 7465 Trondheim, Norway C. Filia`tre UFR des Sciences et Techniques, Universite´ de Franche-Comte´, 25030 Besancon, France 123 J Sol-Gel Sci Technol (2010) 54:249–257 DOI 10.1007/s10971-010-2190-0