Silicon Monomer Formation and Surface Patterning of Si(001)-2 × 1 Following Tetraethoxysilane Dissociative Adsorption at Room Temperature

Abstract

The adsorption of tetraethoxysilane (TEOS, Si[OC2H5]4) on the Si(001)-2 × 1 surface at 300 K is studied through a joint experimental and theoretical approach, combining scanning tunneling microscopy (STM) and synchrotron radiation X-ray photoelectron spectroscopy (XPS) with first-principles simulations within the density functional theory (DFT). XPS shows that all Si–O bonds within the TEOS molecules are broken upon adsorption, releasing one Si atom per dissociated molecule, while the ethoxy (−OC2H5) groups form new Si–O bonds with surface Si dimers. A comparison between experimental STM images and DFT adsorption configurations shows that the four ethoxy groups bind to two second-neighbor silicon dimers within the same row, while the released silicon atom is captured as a monomer on an adjacent silicon dimer row. Additionally, the surface displays alternate ethoxy- and Si adatom-covered rows as TEOS coverage increases. This patterning, which spontaneously forms upon TEOS adsorption, can be used as a template for the nanofabrication of one-dimensional self-organized structures on Si(001)-2 × 1.