Self-assembled silane molecules are commonly used in a wide variety of electrolyte-insulator-silicon fieldeffect transistors. We combine capacitance-voltage measurements with equivalent-circuit modeling to study such a structure, where the main steps of the self-assembly process, namely surface solvent-cleaning, surface activation, and self-assembly, were sequentially characterized. It is found that UV radiation (254 nm) used in the cleaning and hydroxylation induces interface states between the Si and SiO2 insulator with a concentration around 1013 cm-2. When the UV radiation is blocked, the interface states concentration is reduced by 1 order of magnitude. Subsequent self-assembly of polar monolayers of 3-aminopropyltrimethoxysilane and 11-aminoundecyltriethoxysilane do not induce any change in the flat-band of the Si when in contact with an electrolyte, in contrast with the same monolayers measured under dry conditions. This is attributed to electrostatic screening by the electrolyte.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Energy (all)
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films