Structural Study of BF₂ Ion Implantation and Post Annealing of BaSi₂ Epitaxial Films

We have investigated the effects of BF₂ ion implantation and subsequent annealing on the structure of epitaxial BaSi₂ thin films with the aim of the fabrication of a p-type B-doped BaSi₂ film. After 10 min of annealing at 600 °C and above, BaSi₂ is lost at least partly accompanied by appearance of Si as evidenced by X-ray diffraction and Raman spectroscopy. Element mapping by energy dispersive X-ray spectroscopy revealed that a barium oxide is formed on the surface, which indicates that BaSi₂ is oxidized into a barium oxide and Si during annealing. Such oxidation was found to be suppressed by employing rapid thermal annealing for 30 s even when the annealing temperatures of 700 and 800 °C were chosen. Analysis of the full width at half maximum of the Raman peak showed that the inhomogeneous stress in the film produced by ion implantation can be decreased to the as-grown level by rapid thermal annealing at 700 and 800 °C for 30 s. At the same time, the red shift of the Raman peak is shown, based on which the possibility of B substitution for Si is discussed.