Incorporation of manganese into semiconducting ScN using radio frequency molecular beam epitaxy

Abstract

The incorporation of manganese into semiconducting ScN, using radio frequency molecular beam epitaxy, has been investigated. X-ray diffraction and reflection high energy electron diffraction measurements show the face-centered tetragonal rocksalt-type crystal structure with Sc and Mn cations and N anions. In addition to the solute incorporation into the lattice, which is clear from the positions of the diffraction peaks, atomic force microscopy images show that the surface of the alloy grown at TS⩽518°C contains dot-like features, indicating surface accumulation. The areal dot density is found to decrease as the growth temperature increases, whereas the Mn incorporation increases at 518 °C. This behavior is suggestive of a thermally activated process, and it is well explained by an Arrhenius law, giving an activation energy (diffusion barrier) of 0.67 eV. Increasing the growth temperature to 612 °C leads to an increased desorption rate, resulting in little Mn incorporation. It has been found that the growth is nearly optimized at TS=518°C for high Mn incorporation, smooth growth, and small accumulate density. The alloy is found to have lattice parameters which depend on the Mn∕(Mn+Sc) bulk ratio. The alloy lattice constants follow Vegard’s law depending on the Mn bulk fraction and the lattice constants of ScN and θ-phase MnN. The Mn incorporation and Mn incorporation coefficient for films grown at TS=518°C increase as the Mn∕(Mn+Sc) flux ratio increases.