Adsorption and thermal dissociation of pyrrole on Si(100)-2 x 1

The adsorption and thermal reaction of pyrrole on Si(1 0 0)-2 x 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 pi-interaction. The increase in coverage causes tilting of chemisorbed molecules towards the surface normal, attributable to the adsorbate-adsorbate interactions. At similar to350 K, the N-H bond scission of the pi-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(l 0 0), 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. (C) 2003 Elsevier B.V. All rights reserved.