AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS2+EM-TuA

Paper SS2+EM-TuA10
Femtosecond Photo-induced Dynamics on a Cleaned and a Chlorinated Si(111) Surfaces

Tuesday, October 26, 1999, 5:00 pm, Room 6C

Session: Semiconductor Surface Chemistry
Presenter: S. Haraichi, Electrotechnical Laboratory, Japan
Authors: S. Haraichi, Electrotechnical Laboratory, Japan
F. Sasaki, Electrotechnical Laboratory, Japan
Correspondent: Click to Email
A photo-induced chemical etching of Si is considered as a powerful candidate of the next-generation device fabrication thechnology from the view point of extremely low damage. However the atomic and/or dynamic mechanisms of the photo-induced reaction of Si/halogen systems have not been well understood. We have investigated photo-induced dynamics on a cleaned and a chlorinated Si(111) surfaces using femtosecond second-harmonic generation (SHG). For the pump-probe measurements, Ti-sapphire laser at 1300nm and 800nm with a 100fs pulse width were used as the probe and the pump beams, respectively. With the wavelength at 1300nm, a contribution of absorption is negligible and the surface specific information can be obtained. SHG intensities from a cleaned 7x7 surface decay rapidly just after the pump beam coincides with the probe beam and increase with a rapid and a slow time constants of around 1ps and more than several tens ps. These results were probably due to an immediate photo-excitation and two kinds of relaxation of 7x7 surface states. On the other hand, SHG intensities from a chlorinated Si surface increase rapidly just after the pump beam irradiation and decay with a time constant of around several ps, based on Si-Cl bonding states. On both a cleaned and a chlorinated Si surfaces, the time constants show no significant dependence on the pump beam fluency under the critical fluency of the etching reaction.