Si-H vibrational mode on a H-Si(111)1 x 1 surface with hydrogen deficiency

We used a dipole coupling theory to calculate modulations of the Si-H vibrational mode on a H Si(111)1 x 1 surface, and analyzed the observed optical sum frequency generation (SFG) spectra. As the hydrogen coverage decreased, the peak position of the Si-H vibrational mode shifted to the red side in the experimental SFG spectra [Hien et al., Surf. Int. Anal., 44 662 (2012)]. The calculated peak shift was quantitatively consistent with the observed redshift, indicating that the peak shift can be attributed to dipole coupling among the Si-H oscillators. On the other hand, the experimental peak widths at lower coverages were wider than those of the calculated peaks. This suggests that local structural defects and/or dangling bonds modulated the vibration of the surrounding Si-H oscillators. (C) 2013 Elsevier B.V. All rights reserved.