Surface Raman scattering study on the hydrogenated semiconductor surfaces:vibrational dephasing dynamics

Surface Raman scattering has been systematically performed on Ge(100)-2 x 1 :H and Ge(111)-1 x 1:H. The temperature-dependent spectral profiles of GeH stretches from 150 to 450 K were analyzed with the Persson-Ryberg dephasing model. The extracted exchange mode for the Ge(100) surface matches the GeH bending mode. However, the corresponding mode for the Ge(111) surface is w ithin the phonon branch. The surface-specific vibrational dephasing behavio r can be attributed to the difference in vibrational coupling between the a dsorbates and the substrate. This behavior and the similar behavior found f or the hydrogenated diamond and silicon surfaces can be explained by a mult i-mode dephasing model. (C) 1999 Elsevier Science B.V. All rights reserved.