Investigation of the Role of the Interplay between Water and Temperature on the Growth of Alkylsiloxane Submonolayers on Silicon

Abstract

We have investigated the influence of the interplay of the temperature and the water concentration in the adsorption solution on the growth of self-assembled monolayers on silicon using octadecyltrichlorosilane as the precursor. Toluene has been used as the solvent. The morphology of the submonolayer films has been investigated by atomic force microscopy (AFM). The surface coverages have been determined both with ellipsometry and through quantitative evaluation of AFM images. The size distribution of species in the precursor solution has been studied with dynamic light scattering. The influence of water concentrations between 8 and 18 mmol/L has been investigated in the temperature range from 2 to 35 degrees C. Dynamic light scattering revealed a unimodal size distribution of ordered aggregates in solution with a hydrodynamic radius of 200 nm regardless of the temperature and water concentration. However, formation of these features was faster at higher water contents and lower temperatures. Moreover, a characteristic temperature, which was higher for higher water concentrations, was found, above which such aggregates could not be detected anymore. Below this temperature an increase of the aggregate concentration has been observed until a plateau had been reached within a temperature range of approximately 5 degrees C. AFM measurements and ellipsometry on the corresponding submonolayer films showed that this temperature range is also associated with a transition from fast growth via characteristic fractally shaped islands to comparatively slow homogeneous growth via adsorption of individual molecules. The results are discussed in terms of diffusion and adsorption limitations.

Engineering Silicon Oxide Surfaces Using Self‐Assembled Monolayers

“…[76] Dynamic light scattering studies revealed the formation of aggregates in solution with a hydrodynamic radius of approximately 200 nm for all examined water concentrations and temperatures. However, formation of the aggregates was faster at higher water contents and lower temperatures.…”

Surface modification of cobalt–chromium–tungsten–nickel alloy using octadecyltrichlorosilanes

“…The exact state of mechanism behind the chemical bonding of OTS on a surface is still debatable. The formation of OTS monolayer on a material surface is highly sensitive to several factors, which include (a) the density of surface hydroxyl groups [32]; (b) reaction temperature [29,33]; (c) reaction environment [34,35]; (d) reaction time [34]; (e) solvent used to deposit OTS [35,36]; (f) water content of the solvent [33]; (g) concentration of OTS [35,37]; (h) solution age [38]; (i) roughness of the underlying substrate [39]; and (j) cleaning procedures after SAM deposition [40].…”

Silicon Based Nanocoatings on Metal Alloys and Their Role in Surface Engineering

“…Glaser et al studied OTS submonolayers and reported that the formation of water aggregates was faster at higher water contents and lower temperatures. A characteristic temperature was found above which the aggregates could no longer be detected and which was higher for higher concentrations [231].…”