Chemisorption and kinetics of Sb on Si(001)

• Published in: Ultramicroscopy 1992, Vol.42 (A), p.884-888
• Main Authors: Elswijk, H.B., van Loenen, E.J.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Physics; Solid surfaces and solid-solid interfaces; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/0304-3991(92)90373-R

We study the room temperature chemisorption of Sb 4 molecules on Si(001) by scanning tunneling microscopy (STM). Most of these molecules dissociate into two Sb 2 dimers. Each dimer binds on top of a Si dimer row by bonding to four unsaturated dangling bonds. The two dimers always remain closely spaced after the chemisorption process. A small fraction of the Sb 4 molecules chemisorbs differently: the resulting atomic configuration images as a rhombus in a filled-state STM micrograph. The mobility of the Sb 2 dimers is studied and an activation energy barrier to diffusion of 1.3±0.2 eV is estimated assuming an attempt frequency of 10 13 Hz. The mobile Sb 2 dimers tend to form strings which act as nuclei for growth of Sb islands. The Sb islands are composed of Sb dimer rows similar to Si islands on Si(001). We do not find preferential incorporation of Sb in Si step edges.