AVS 52nd International Symposium
    Surface Science Tuesday Sessions
       Session SS3-TuA

Paper SS3-TuA4
Wavelength-Dependent Infrared Laser Induced Hydrogen Desorption from a Si(111) Surface

Tuesday, November 1, 2005, 3:00 pm, Room 206

Session: Ultrafast Surface Dynamics
Presenter: Z. Liu, University of Minnesota, Vanderbilt University
Authors: Z. Liu, University of Minnesota, Vanderbilt University
P.I. Cohen, University of Minnesota
L.C. Feldman, Vanderbilt University
N.H. Tolk, Vanderbilt University
Z. Zhang, Oak Ridge National Laboratory
Correspondent: Click to Email
Wavelength-dependent infrared laser induced hydrogen desorption from a Si(111) surface hydrogen passivation on silicon surfaces is a bottleneck in low temperature Si homoepitaxy. We employ infrared laser radiation from the Vanderbilt Free-Electron Laser to desorb hydrogen from a Si(111) surface at a temperature below 300C where thermal effects are minimal. The vibrational mode of the Si-H bond was excited by the infrared laser to enhance hydrogen desorption. The cross-section of the coupling between the laser and the Si-H bonds has been measured as a function of laser wavelength and power, showing a resonant effect at the energy of the vibrational mode at 2087 cm@super -1@. The desorption rate was maximized when the polarization of the light was maximized along the Si-H bond direction. The vibrational energies of the Si-H bond are different at terrace sites and step sites. Thus this mechanism provides a way to selectively desorb hydrogen atoms from different locations on the Si surface, and allows site-selective epitaxial growth of Si. To our knowledge this it the first report of wavelength-selective desorption of an adsorbate on a semiconductor surface. This project is partially supported by DARPA/SPAWAR grant N66001-04-1-8924 and DOE grant ER45781.