title: Detailed structural examinations of covalently immobilized gold nanoparticles onto hydrogen-terminated silicon surfaces.
abstract: The modification of flat semiconductor surfaces with nanoscale materials has been the subject of considerable interest. This paper provides detailed structural examinations of gold nanoparticles covalently immobilized onto hydrogen-terminated silicon surfaces by a convenient thermal hydrosilylation to form Si-C bonds. Gold nanoparticles stabilized by omega-alkene-1-thiols with different alkyl chain lengths (C3, C6, and C11), with average diameters of 2-3 nm and a narrow size distribution were used. The thermal hydrosilylation reactions of these nanoparticles with hydrogen-terminated Si(111) surfaces were carried out in toluene at various conditions under N2. The obtained modified surfaces were observed by high-resolution scanning electron microscopy (HR-SEM). The obtained images indicate considerable changes in morphology with reaction time, reaction temperature, as well as the length of the stabilizing omega-alkene-1-thiol molecules. These surfaces are stable and can be stored under ambient conditions for several weeks without measurable decomposition. It was also found that the aggregation of immobilized particles on a silicon surface occurred at high temperature (> 100 degrees C). Precise XPS measurements of modified surfaces were carried out by using a Au-S ligand-exchange technique. The spectrum clearly showed the existence of Si-C bonds. Cross-sectional HR-TEM images also directly indicate that the particles were covalently attached to the silicon surface through Si-C bonds.
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Yamanoi
authors.forename: Naoto
authors.initials: N
authors.lastname: Shirahata
authors.forename: Tetsu
authors.initials: T
authors.lastname: Yonezawa
authors.forename: Nao
authors.initials: N
authors.lastname: Terasaki
authors.forename: Noritaka
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Matsui
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Nishio
authors.forename: Hideki
authors.initials: H
authors.lastname: Masuda
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ikuhara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishihara