IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Tuesday Sessions
       Session SS3-TuP

Paper SS3-TuP14
Desorption of Silicon Chloride and Formation of Dimer-Adatom-Stacking Fault Structure on Si(111) Studied by Surface Differential Reflectivity Spectroscopy

Tuesday, October 30, 2001, 5:30 pm, Room 134/135

Session: Adsorption/Desorption Poster Session
Presenter: M. Tanaka, Yokohama National University, Japan
Authors: M. Tanaka, Yokohama National University, Japan
S. Minami, Yokohama National University, Japan
K. Shudo, Yokohama National University, Japan
Correspondent: Click to Email
The processes of isothermal desorption of silicon chloride from the chlorine-saturated Si(111)1x1 surface has been investigated by means of in-situ real-time surface differential reflectivity (SDR) spectroscopy. Temperature range was 873-933K. SDR spectra at each temperature were obtained by the normalization with the reflectance spectrum of the clean surface having 7x7 dimer-adatom-stacking fault (DAS) structure. The spectral features observed at 1.8 and 2.5eV come from missing of adatom dangling bonds and adatom back bonds of DAS structure, respectively. The feature at 1.8eV is found to be removed faster than that at 2.5eV due to the desorption of silicon chloride, which means that the feature at 1.8eV originates from not only adatom dangling bonds but also dangling bonds on the 1x1 surface. The restoration of the dangling bonds therefore represents the development of the desorption. The desorption process is found to follow first order kinetics, suggesting the mechanism that SiCl supplied from clusters and/or steps on the chlorine-saturated Si(111)1x1 surface recombines with Cl on the surface and SiCl@sub 2@ species is desorbed. The activation energy of this process is obtained as 2.2eV from the temperature dependence of the rate constant. On the other hand, the restoration of the back bonds represents the formation of DAS structure after the desorption. The restoration process is found to follow also first order kinetics, and the activation energy is obtained as 2.8eV. The mechanism of the desorption of silicon chloride and the formation of DAS structure is discussed from these activation energies in terms of potential barriers.