One-dimensional ordered structure of C2H4 on a Si(001) surface

Abstract

A one-dimensional (1-D) ordered structure of ethylene (C2H4) molecules on a Si(001) surface has been investigated by using coaxial impact collision ion scattering spectroscopy (CAICISS) and computer simulations. In a previous paper, the di-sigma on-top site of the Si(001)-(2 x 1) surface was exposed at room temperature (RT) to 1001, (IL = 10(-6) Torr.sec)of C2H4 molecules, which were intially absorbed on that surface. With increasing number of C2H4 molecules, a structural change of C2H4/Si(001)-(2 x 1) surface was observed by using the low-energy electron diffraction (LEED). When the Si(001)-(2 x 1) surface at RT to 2001, of C2H4 molecules, the C2H4 molecules occupied the di-sigma on-top site on the Si(001)-(2 x 1) surface. With the help of a computer simulation, the C-C and Si-C bond lengths were found to be 1.61 +/- 0.05 angstrom and 1.81 +/- 0.05 angstrom respectively. The C2H4 molecules were also found to be adsorbed on the Si(001) surface on in tandem along the direction of Si dimer-rows. This result provides evidence supporting the mechanism of 1-D nano-structure formation based on the C2H4 molecules on Si(001) surface.