Abstract
Ordered submonolayers of adsorbate atoms on semiconductor surfaces constitute a playground for electronic correlation effects, which are tightly connected to the local atomic arrangement and the corresponding vibration eigenmodes. We report on a study of the vibration eigenmodes of Au-covered Si(111) surfaces with reconstruction using polarized Raman spectroscopy and first-principles calculations. Upon Au coverage, the vibration eigenmodes of the clean reconstructed Si(111)- surface are quenched and replaced by new eigenmodes, determined by the Au- reconstruction. Several polarization-dependent surface eigenmodes emerge in the spectral range from 25 to , with the strongest ones at 29, 51, and . In our first-principles calculations we have determined the vibration frequencies, the corresponding elongation patterns, and the Raman intensities for two different structure models currently discussed in the literature. The best agreement with the experimental results is achieved for a model with 0.7 monolayer coverage and seven Au atoms per unit cell, proposed by S. G. Kwon and M. H. Kang [Phys. Rev. Lett. 113, 086101 (2014)].
- Received 13 October 2016
- Revised 21 November 2016
DOI:https://doi.org/10.1103/PhysRevB.94.235304
©2016 American Physical Society