Bonding self-assembled, compact organophosphonate monolayers to the native oxide surface of silicon

Hanson E., Schwartz J., Nickel B., Koch N., Danisman M. F.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol.125, no.51, pp.16074-16080, 2003 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 125 Issue: 51
  • Publication Date: 2003
  • Doi Number: 10.1021/ja035956z
  • Journal Name: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.16074-16080
  • Middle East Technical University Affiliated: Yes

Abstract

A new method is described to prepare strongly bonded, compact monolayer films of alkyl- or arylphosphonates on the native oxide surface of Si (SiO2/Si). This method is illustrated for octadecyl- and alpha-quarterthiophene-2-phosphonates. For both cases, AFM shows comprehensive coverage of the SiO2/Si surface. The thickness of the continuous film of 4TP/SiO2/Si was measured both by AFM and by X-ray reflectivity to be ca. 18 Angstrom. Direct gravimetric analysis shows surface coverage by alpha-quarterthiophene-2-phosphonate to be about 0.66 nmol/cm(2), which corresponds to molecular packing in the film close to that of crystalline alpha-quarterthiophene. Coverage by octadecylphosphonate was ca. 0.90 nmol/cm(2), corresponding to a cross-sectional area of about 18.5 Angstrom(2)/molecule, consistent with close-packed alkyl chains.