EFFECT OF TEMPERATURE AND SURFACE COVERAGE ON THE SAMARIUM INTERACTION WITH SI(111)

The interaction of Sm atoms with Si(111) has been studied. The study w as carried out by low-energy electron diffraction, Auger-electron spec troscopy, and contact-potential difference method over a broad range o f temperatures (from room temperature to 1140 K) at which samarium was deposited on the silicon sample surface. The surface coverage varied from zero to 55 monolayers. It was shown that the shape of the low-ene rgy Auger spectrum of samarium depends on coverage, and that its varia tion correlates with that of the Sm atom valence state. It was establi shed that no ordered structures form when samarium is deposited on sil icon at room temperature, and that partial mixing of the metal and sem iconductor atoms takes place in the initial stages of this process. If samarium is deposited on heated silicon (900 and 1140 K), an adsorbed film (transition layer), whose structure is determined by the coverag e and temperature, is the first to form. After that, three-dimensional silicide crystallites begin to grow on this transition layer. Their s hape depends on the substrate temperature. This dependence accounts fo r the relation between temperature and the coverage at which the cryst allites coalesce. (C) 1998 American Institute of Physics. [S1063-7834( 98)03510-2].