Doping of β-FeSi2 Thin Film with Aluminum Prepared by Molecular Beam Epitaxy

Abstract

β-FeSi2 film has been doped with Al for p-type conductivity by molecular beam epitaxy. The doping concentration was controlled by the temperature of the Kundsen effusion cell (K-cell). It was found that the conductivity type remained unchanged as n-type at a K-cell temperature lower than 825 °C, and it changed into p-type above 850 °C. As the K-cell temperature increased, the net carrier concentration increased and the Hall mobility decreased. X-ray diffraction showed predominantly (110)/(101)-oriented epitaxial growth containing polycrystalline components with Al doping. Scanning electron microscope and secondary ion mass spectroscopy measurements revealed that Al segregated and precipitated at the surface grain boundaries during annealing. Al-doped films exhibited continuous structures without cracks or pinholes. The results suggest that Al is a possible p-type dopant.