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 b een investigated by core-level and valence-band photoemission using sy nchrotron radiation. The experimental results show the existence of di stinct stages corresponding to chemisorption and agglomeration of Sm a toms(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 in terdiffusion of Sm and Si is observed. Like on Si(111), a multiphase i nterface is formed but less stable. After being annealed, this phase d isappears gradually. When the annealing temperature gets up to 1000 de grees C, an original 2x1 LEED patterns appear again on the surface. To gether with a model, the interface formation and the interface profile is discussed in detail in the text.