Selective patterning of covalent molecular grafting on doped amorphous silicon templates

Abstract

AbstractLinear alkene molecules have been covalently immobilized on amorphous silicon surfaces. The larger thermal reactivity of n+‐doped vs. nominally undoped a‐Si:H surfaces towards perfluorodecene (PFD) molecules in the gas phase has been exploited to investigate a selective patterning of molecular grafting on a previously defined template of doped / undoped regions. PFD has been chosen to obtain hydrophobic monomolecular layers with fluorine labelling, useful for photoelectron spectroscopy (XPS) and NanoSIMS imaging.The template was obtained by growing undoped a‐Si:H on top of n+ a‐Si‐H, and defining 40 μm‐edge patterns of undoped a‐Si:H by reactive ion etching in a (CF4, O2) mixture. After native oxide removal, the patterned surface was exposed to PFD at 230 °C. NanoSIMS images, taken at increasing Cs+ irradiation doses, show the expected 19F and 28Si contrast on as‐grafted surfaces; this contrast disappears after ∼340 seconds Cs+ irradiation, corresponding to the desorption of the PFD monomolecular layer. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)