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Keywords:

  • B and N impurities;
  • first-principles calculations;
  • nanoribbons;
  • SiC

Abstract

Zigzag silicon carbon nanoribbons (ZSiC NRs) containing one substitutional nitrogen (N) or boron (B) atom in each super cell that includes four units are investigated by first-principles calculations. It is found that the system where one of the edge Si atoms was substituted by a B atom presents ferromagnetic half-metallic behavior, while the system where one of the edge C atoms was substituted by an N atom shows ferrimagnetic half-metallic behavior. Moreover, in contrast to the pristine system, where the edge magnetism appears at both edges, the edge magnetism of the B-doped system only appears at the C edge, while the edge magnetism of the N-doped system only appears at the Si edge. These are because a B atom substituting one of the edge Si atoms destroys the local spin moment at the edge Si atoms, but an N atom substituting one of the edge C atoms destroys the local spin moment at the edge C atoms. When the size of the super cell increases to six units, the dilute doping case, the local spin moment at some edge atoms, where the substitution impurity resides at the edge, remains. This means that the dilute doping fails to completely destroy the local spin moment at the edge atoms, where the impurity resides at the edge. However, the half-metallic band structure remains in the dilute doping case. Thus, a B atom substituting one of the edge Si atoms, as well as an N atom substituting one of the edge C atoms, induces a semiconductor–half-metallic transition in the ZSiC NRs.