Stratification of the Fe/Si(001)2x1 interface by heat treatment of the wetting layer

Abstract

The study was carried out by LEED, AES, EELS and AFM methods. Films of Fe/Si(001)2x1 were obtained at substrate temperatures of 30oC and source temperatures of 1250oC. Wetting layer (WL) Fe on Si(001)2x1 was formed by two-stage annealing at temperatures and thicknesses of 500oC and 250oC and 1 monolayer (ML) and 3 ML, respectively. Analysis and interpretation of the data obtained, taking into account possible reaction patterns, showed that after annealing at 1 ML thickness, the Fe composition corresponded to 2 ML Si/Fe. Further, at 2 ML, it changed to Fe/Si/Fe, at 3 ML, it changed to Fe-FeSi, and after annealing, to FeSi. At 4 ML, there was formation of FeSi/FeSi2 film. And, further, at 7 ML and 10 ML, the composition of the films became Fe3Si/FeSi2 and, respectively, Fe/Fe3Si/FeSi2. At the same time, the upper Fe3Si layers were coated with 0.6 ML and the Fe layers with 0.3 ML of segregated Si atoms, which number increased, after annealing at 250oC, to 0.6 ML in the latter case. In the obtained Fe film, the size and average grain height were 10-20 nm and, respectively, ~0.4 nm. Keywords: interface, wetting layer, multilayer film, layer composition, surface reaction patterns, Fe, Si(001)2x1.