Scanning tunneling microscopy study of the early stages of epitaxial growth of CoSi2 and CoSi films on Si(111) substrate: Surface and interface analysis

作者：Kotlyar V G^*; Alekseev A A; Olyanicha D A; Utas T V; Zotov A V; Saranin A A

来源：Thin Solid Films, 2016, 619: 153-159.

DOI：10.1016/j.tsf.2016.11.006

• Thin films
• Cobalt
• Silicon(111)
• Cobalt silicides
• Interface structure
• Scanning tunneling microscopy
• Density functional theory

We report scanning tunneling microscopy observations of solid-phase epitaxial growth of ultra-thin CoSi2 and CoSi films at heating temperatures in the range of 350-600 degrees C using a disordered '(1 x 1)' phase of Co/Si(111) as a pre-existing template. It is found that depending on the growth conditions two types of epitaxial cobalt silicide films can be formed. At coverages below similar to 2ML (1ML= 7.83 x 10(14) atoms/cm(2)) of Co, CoSi2 phase grows in the form of flat two-layer patches spreading over the surface at elevation of the temperature. It consists of precisely two the completely filled Co layers and four Si layers above the interface. At coverages higher than similar to 2 ML of Co, the layer-by-layer growth of CoSi phase with the CsCl-type crystal structure also takes place. The CoSi phase consists of one or more Co-Si double layers, which are located on top of the second Si-Co-Si triple layer of CoSi2, i.e., it has. coherent double interface CoSi/CoSi2/Si(111). According to experimental findings and ab initio total-energy calculations, the structures with the eightfold coordination of interfacial Co atoms and lateral unit cells of the silicide layer and substrate mutually rotated by 180 degrees prove to be the most stable ones.

• 出版日期2016-11-30