IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Wednesday Sessions
       Session SS+SC-WeM

Paper SS+SC-WeM3
High-Resolution Core-Level Study of the Initial Stage of Oxygen Adsorption on a Si(111)-(7x7) Surface

Wednesday, October 31, 2001, 9:00 am, Room 122

Session: Adsorption on Semiconductor and Metal Oxide Surfaces
Presenter: K. Sakamoto, Linköping University, Sweden
Authors: K. Sakamoto, Linköping University, Sweden
H.M. Zhang, Linköping University, Sweden
R.I.G. Uhrberg, Linköping University, Sweden
Correspondent: Click to Email
As motivated by the technological importance of thin silicon oxide films in semiconductor devices, the initial stage of oxygen adsorption on silicon surfaces has been a topic of experimental and theoretical investigations. Among the various reports on oxygen adsorption, Si 2p core-level studies have played crucial roles in elucidating the structures of the SiO@sub 2@/Si interfaces. However, very few Si 2p studies are available for the initial stage of oxygen adsorption on a Si(111)-(7x7) surface. In this paper, we present a high-resolution Si 2p core-level photoemission study of submonolayer oxygen adsorption on the (7x7) surface. The photoemission measurements were performed at beamline 311 at the MAX-II synchrotron radiation facility in Lund, Sweden. The clean (7x7) surface was exposed to 0.1-20 L of oxygen at 120 K, which correspond to coverages below 1 ML. Significant intensity of the Si 2p component due to the Si@super 2+@ species is observed already at 0.3 L, and the component due to the Si@super 3+@ species is clearly observed at a dosage higher than 1.0 L. These results indicate that more than two oxygen atoms adsorb to one Si atom even at a very low coverage. After annealing the oxygen adsorbed sample at 600 K, the Si 2p component due to the Si@super 2+@ species shows a shift of 0.4 eV to the higher binding energy side. This result suggests different atomic configurations for the Si@super 2+@ species at 120 K and after annealing the sample at 600 K. We will also present detailed studies of the dosage- and temperature-dependent intensities of the Si 2p components due to the suboxide species.