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Keywords:

  • silicon carbide;
  • structural properties;
  • vacancy formation;
  • N-doping;
  • computer simulations

Abstract

SiC polytypes in bulk form is systematically investigated using ab initio pseudopotential approach for the total energy calculations in four structures such as 3C (zinc blende), 6H, 4H, and 2H (wurtzite) structures with vacancy and nitrogen doping. Our calculated energy differences ΔE among four structures reveal that 3C and 4H are favorable for prefect SiC. The ΔE for SiC with vacancy suggests the most stable structures such as 6H with Si-vacancy and 4H with C-vacancy. The calculated vacancy formation energies suggest that C-rich condition prefers 6H whereas 4H is favored under Si-rich condition. Furthermore, nitrogen substituting for carbon and silicon respectively stabilizes 3C and 4H. These calculated results are consistent with experimental findings. The destabilization due to the vacancy formation and stabilization due to nitrogen of 3C-SiC are discussed by bond charge calculations and our simple formula of ΔE. It is found that vacancy formation inducing large deficit of bond charges favors 6H- and 4H-SiC and nitrogen-doping increasing bond charges stabilizes 3C-SiC. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)