Influence of Surfactants(Ag, Sn) in Si/Si(111) Homoepitaxial Growth

We have the homoepitaxiallayers on the surfaces of Si(111) with and without the adsorbed surfactants, for example, Ag or Sn. In this paper, We have studied the difference of growth for these two cases by the observation of intensity oscillations of RHEED specular spots during the growing processes. In the case of growth without the adsorbed surfactants, the Si atoms fill first the stacking fault layer of Si(111) 7 7 structure. Therefore, the irregular oscillations are observed in the early stage of growing process. However, in the case of growth with the adsorbed surfactants, the surfactants already have the structures on the surfaces of Si(111) at the adjucate temperatures of 300` and 190~ for the surfactants of Ag and Sn, respectively. We also find that the number of oscillations is a little larger for the case of growth with the adsorbed surfactants. The reason for this is that for the case of growth with the adsorbed surfactants, the activation energies of Si atoms decrease due to the segregation of surfactants toward the growing surfaces.