Surface Infrared Studies of Silicon/Silicon Oxide Interfaces Derived from Hydridosilsesquioxane Clusters

Abstract

Hydridosilsesquioxane-based model systems have been developed over the past five years to help elucidate the structure and reactivity properties of silicon/silicon oxide interfaces. In this paper, the assignment of infrared bands as Si−O or Si−H derived is explored via deuterium labeling studies. In particular, the issue of the presence of adventitious water in the model interfaces is directly addressed via the chemisorption of deuterated-spherosiloxane clusters (D8Si8O12) onto clean Si(100). The experiments definitively demonstrate that there are no water-derived features detectable by RAIRS in the model interfaces. This rules out water contamination as a possible explanation for the 1.0 eV shifted feature observed in Si 2p core-level spectroscopy for the model systems. This work is further supported by cluster and water co-dosing experiments on Si(100), which address the spectroscopic sensitivity of surface silicon−hydrides in this system. Finally, the first surface crystallographic studies of the model interfaces performed with LEED are presented. The chemisorbed hydridosilsesquioxane model systems are shown to retain the 2×1 reconstruction of the original Si(100) surface.

Simulated scanning tunneling microscopy images of three-dimensional clusters:H8Si8O12onChen1, Schneider2, Holl3 et al. 2004Phys. Rev. B

“…The monovertex attachment model contains the following key propositions: (1) the cluster cage remains intact, (2) the cluster is activated at one of the Si-H vertices, and (3) the cluster bonds to a Si dimer atom via a single Si-Si bond. [9][10][11][12] The cracked cluster model features Si-O bond scission along a cluster cage edge, resulting in a bridged bonding configuration across a Si dimer. 13,14 For these models, the Si 9 H 12 cluster was employed to simulate the silicon surface dimer to which the cluster is bonded.…”

“…The structure of H 8 Si 8 O 12 clusters chemisorbed on Si͑100͒-2 ϫ 1 has been previously characterized using x-ray photoemission spectroscopy (XPS), 9,10 reflection absorption infrared spectroscopy (RAIRS), 11 and STM. 12 As a model system used to determine the XPS binding assignments for the study of amorphous silicon oxide, the veracity of many papers rests on the determination of the correct binding mode.…”

“…Currently, two bonding models for the chemisorbed product have been proposed: experimental evidence has pointed towards the monovertex attachment model [ Fig. 1(a)], [9][10][11][12] whereas theoretical studies have suggested the cracked cluster model [ Fig. 1(b)].…”

The reaction of H8Si8O12 with a chromium oxide surface: a model for stainless steel surface modification

“…Details of this experimental apparatus are described elsewhere. 28 Experiments typically involved taking a background spectrum, performing the desired CVD and then taking a second spectrum. The ratio of this second spectrum to the background was then calculated to arrive at the final plot.…”

New Structural Model forSi/SiO2Interfaces Derived from Spherosiloxane Clusters: Implications for Si2pPhotoemission Spectroscopy

“…They found that the calculated features were totally inconsistent with the experimentally observed peaks at lower binding energies, and suggested that the actual surface structure may be "more complex." Though more related work on this system has been performed [7][8][9][10], this discrepancy between theory and experiment has not been resolved.…”