Solid-phase growth and structure of barium disilicide films on Si (111)

The paper presents the results of an experiment on the formation of thin films of barium disilicide (BaSi₂) – a promising material for solar cells using the method of solid-phase epitaxy.  BaSi₂ was formed in ultrahigh vacuum on silicon substrates with the use of template technology. At the final stage of the formation of nanostructures the films were recrystallized by annealing. The resulting thin films were investigated by in-situ methods: Auger electron spectroscopy and electron energy loss spectroscopy. Then ex-situ techniques were used: atomic force microscopy and X-ray diffraction. The latter method showed the presence of a-oriented barium disilicide in the film formed at the temperature of recrystallization T = 800 ⁰ C. The spectra of Auger electrons and electron energy loss for the film are presented. The analysis of surface topology nanostructure obtained by atomic force microscopy shows that its surface roughness is comparable with the roughness of thin BaSi₂ film samples formed by molecular beam epitaxy. The reason for a small amount of crystallites BaSi₂ formed, as we see it, is low interdiffusion of barium and silicon atoms in the case of using the chosen method of forming a film. The use of the Ba and Si co-deposition technique, followed by recrystallization of the film at temperatures close to the temperature specified in the paper appears to be the solution of this problem.