Adsorption and thermal dissociation of pyrrole on Si(1 0 0)-2 × 1

Abstract

The adsorption and thermal reaction of pyrrole on Si(100)-2×1 have been studied using X-ray and ultra-violet photoelectron spectroscopies (XPS and UPS) and high resolution electron energy loss spectroscopy (HREELS). At low exposures, Pyrrole chemisorbs molecularly at 120 K with its ring parallel to the surface via the π-interaction. The increase in coverage causes tilting of chemisorbed molecules towards the surface normal, attributable to the adsorbate-adsorbate interactions. At ∼350 K, the N-H bond scission of the π-bonded species occurs, resulting in Si-H and vertically N-bonded pyrrolyl on the surface. The pyrrolyl species is thermally stable to 700 K. Compared to furan or thiophene on Si(100), this higher thermal stability is ascribed to the passivation effect of the H-atoms from N-H bond dissociation and the less strain within the pyrrolyl-substrate complex. Further annealing to 900 K results in the formation of silicon carbide and silicon nitride on the substrate. © 2003 Elsevier B.V. All rights reserved.