title: Structure of n-Alkyltrichlorosilane Monolayers on Si(100)/SiO2.
abstract: The structure of n-alkyltrichlorosilane self-assembled monolayers (SAMs) of alkyl chain lengths n = 12, 14, 18, and 22 formed on the amorphous native oxide of silicon (100) has been investigated via angstrom-resolution surface X-ray scattering techniques, with particular focus on the proliferation of lateral order along the molecules' long axis. Grazing incidence diffraction shows that the monolayer is composed of hexagonally packed crystalline-like domains for n = 14, 18, and 22 with a lateral size of about 60 Å. However, Bragg rod analysis shows that ∼12 of the CH2 units are not included in the crystalline-like domains. We assign this, and the limited lateral crystallites' size, to strain induced by the size mismatch between the optimal chain-chain and headgroup-headgroup spacings. Analysis of X-ray reflectivity profiles for n = 12, 14, and 22 shows that the density profile used to successfully model n = 18 provides an excellent fit where the analysis-derived parameters provide complementary structural information to the grazing incidence results.
authors.affiliation: Crystallography and Structural Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg , 91058 Erlangen, Germany.|Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: H-G
authors.initials: HG
authors.lastname: Steinrück
authors.affiliation: Crystallography and Structural Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg , 91058 Erlangen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Will
authors.affiliation: Physics Department, Friedrich-Alexander-Universität Erlangen-Nürnberg , 91058 Erlangen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Magerl
authors.affiliation: Condensed Matter Physics & Materials Science Department, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: B M
authors.initials: BM
authors.lastname: Ocko