Chemical vapor deposition of three aminosilanes on silicon dioxide: surface characterization, stability, effects of silane concentration, and cyanine dye adsorption.

Covalently bonded monolayers of two monofunctional aminosilanes (3-aminopropyldimethylethoxysilane, APDMES, and 3-aminopropyldiisopropylethoxysilane, APDIPES) and one trifunctional aminosilane (3-aminopropyltriethoxysilane, APTES) have been deposited on dehydrated silicon substrates by chemical vapor deposition (CVD) at 150 °C and low pressure (a few Torr) using reproducible equipment. Standard surface analytical techniques such as x-ray photoelectron spectroscopy (XPS), contact angle goniometry, spectroscopic ellipsometry, atomic force microscopy, and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) have been employed to characterize the resulting films. These methods indicate that essentially constant surface coverages are obtained over a wide range of gas phase concentrations of the aminosilanes.