Photoemission study of the Sm/Si(100)2x1 interface

The behavior of interface formed by growing thin Sm film on the Si(100)2x1 substrate at room temperature and its temperature evolution has been investigated by core-level and valence-band photoemission using synchrotron radiation. The experimental results show the existence of distinct stages corresponding to chemisorption and agglomeration of Sm atoms(coverage theta<0.5ML), reactive interdiffusion(0.5<theta<4-6ML), and growth of metallic Sm. Compared to Si(111)7x7 the reactivity of Sm on the Si(100)2x1 substrate is enhanced and a greater tendency for interdiffusion of Sm and Si is observed. Like on Si(111), a multiphase interface is formed but less stable. After being annealed, this phase disappears gradually. When the annealing temperature gets up to 1000 degrees C, an original 2x1 LEED patterns appear again on the surface. Together with a model, the interface formation and the interface profile is discussed in detail in the text.