CONTRIBUTION TO THE STUDY OF THE DYNAMICAL PROPERTIES OF THE B-SI(111) ROOT-3X-ROOT-3 SURFACE - EFFECT OF THE DOPANT BEHAVIOR, FROM THE INFRARED TO THE VISIBLE ENERGY-RANGE

High resolution energy electron loss spectroscopy have been performed on boron implanted Si(lll) surfaces. We have studied the evolution of the HREELS spectrum as a function of the annealing temperature (from 750 degrees C to 1100 degrees C). At 750 degrees C we observe the appearance of the root 3x root 3 superstructure which persists up to 1000 degrees C. We get two main results in the infrared energy range. The first one is the evolution, due to the dopant diffusion, of the energetic position of a loss peak located at approximately 150 meV. The second one is the appearance of a sharp loss feature at 56 meV. It corresponds to the Si-Si frequency (optical phonon) and is correlated to the existence of a charge transfer due to the B sites in the reconstruction.