Self-assembled monolayers of partially fluorinated alcohols on Si(001): XPS and UV-photoemission study

Abstract

Abstract Polyfluorinated alcohols, dissolved in dichloromethane or dilute acetonitrile/water solution of β-cyclodextrin (β-CD) were reacted with the hydrogen terminated Si(0 0 1) surface making interfacial bonds. The UV-induced reaction was followed by X-ray and UV photoelectron spectroscopy (XPS and UPS). The calculated carbon (C1s) XPS spectra obtained via B3LYP/6-311G(d,p) made it possible to assign the binding energies of the electronic states of the carbon atoms from the groups CFH , CF2 and CF3. The density of states (DOS) and highest occupied molecular orbital—lowest unoccupied molecular orbital (HOMO–LUMO) gap (Eg) of aliphatic polyfluorinated alcohols were calculated. The theoretical and experimental data i.e. work function (WF) and ionization energy (Ie) were analyzed. The dependence of Eg value on the surface effects was found to be determined by the number of fluorine atoms in the alcohol molecules.