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Bonding Self-Assembled, Compact Organophosphonate Monolayers to the Native Oxide Surface of Silicon

2003; American Chemical Society; Volume: 125; Issue: 51 Linguagem: Inglês

10.1021/ja035956z

1943-2984

Enobong Hanson, Jeffrey Schwartz, Bert Nickel, Norbert Koch, M. Fatih Danışman,

Conducting polymers and applications

A new method is described to prepare strongly bonded, compact monolayer films of alkyl- or arylphosphonates on the native oxide surface of Si (SiO(2)/Si). This method is illustrated for octadecyl- and alpha-quarterthiophene-2-phosphonates. For both cases, AFM shows comprehensive coverage of the SiO(2)/Si surface. The thickness of the continuous film of 4TP/SiO(2)/Si was measured both by AFM and by X-ray reflectivity to be ca. 18 A. 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 A(2)/molecule, consistent with close-packed alkyl chains.