X-ray photoelectron spectroscopy studies on single crystalline β-FeSi₂

In order to realize the photoluminescence of semiconducting β-FeSi₂ homoepitaxial films, surface preparation of single crystalline β-FeSi₂ is of critical importance. An atomically flat and clean substrate surface of β-FeSi₂ was prepared by sputtering with 2 keV Ar⁺ ions or by heating at 850 °C. The structure of the native surface oxide and the removal of this layer were investigated though X-ray photoelectron spectroscopy measurements. No significant deviation of the stoichiometry was detected in the surface region. Our results suggest that a surface prepared in this way is an eligible substrate for homoepitaxy of β-FeSi₂. - Highlights: • A clean surface of single crystalline (beta)-FeSi₂ was prepared by Ar⁺ sputtering or by heating. • The removal of surface oxide during the surface treatment is elucidated. • The native surface oxides are identified as SiO₂ on top and SiO_x as the inner layer. • There is no significant deviation of surface stoichiometry on the clean surface.