Final evidence for H termination of HF-treated Si surfaces: a comparative study by high-energy and vibrational spectroscopies

The aim of this article is to provide a comparative analysis of Si(100) sur faces after etching in HF in order to attain final conclusions concerning t he chemical termination of the surface. We report a comparative study of th e Si surface chemistry carried our simultaneously using both vibrational an d high-energy techniques. While vibrational spectroscopies (high-resolution electron energy loss spectroscopy as well as multiple internal reflection infrared spectroscopy) show no evidence of the presence of Si-F bonds, Auge r spectroscopy provides clues on the presence of small amounts of F at the surface. Such apparently contradictory results have, in the past, raised do ubts about the actual way surface bonds are saturated. It will be shown tha t fluoride ions are actually present on the Si surfaces as ionosorbed speci es, while Si bonds are exclusively saturated by H atoms. We will further co nfirm how the Si(100) surface chemically etched in diluted HF is terminated not only by SiH2 groups, but also by mono- and trihydrides as a result of the nano-roughening induced by the etching processing. Low-energy electron diffraction analyse confirm and corroborate these conclusions, as they show diffraction maps from highly disordered (2 x 1) reconstructed surfaces. (C ) 2000 Elsevier Science S.A. All rights reserved.