Aldehydes react with scribed silicon to form alkyl monolayers Characterization by ToF-SIMS suggests an even–odd effect

Alkyl monolayers are formed when silicon is chemomechanically scribed in the presence of aldehydes (from butanal to nonanal). X-ray photoelectron spectroscopy (XPS), wetting, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) suggest increasingly thick and hydrophobic monolayers with increasing aldehyde chain length. Superimposed on the general trend of stronger ToF-SIMS signals for hydrocarbon fragments from longer aldehyde precursors is an even–odd effect. This effect is most pronounced for smaller (one- and two-carbon) hydrocarbon fragments and for monolayers prepared with shorter aldehyde precursors. This is the first time than an even–odd effect has been demonstrated for monolayers on scribed silicon. # 2004 Elsevier B.V. All rights reserved.