The stability of SiC polytypes has been studied for many decades due to discrepancies between theory and experiments. In this work, we employ first-principles calculations within the harmonic approximation (HA) to investigate the energetic stability of polytypes as a function of temperature for pure SiC and doped SiC. Different exchange–correlation functionals, including LDA, PBE, and van der Waals corrections, PBE-TS, and DFT-D2, are considered for comparison of the results. Phonon density of states, entropy, heat capacity, and Helmholtz free energy are analyzed to understand polytype stability. Our free energy results show that LDA, PBE, and PBE-TS predict consistent stability trends among polytypes, whereas DFT-D2 shows a different trend and predicts 3C as the most favorable polytype. These findings give a comprehensive understanding of SiC polytype stability and provide valuable insights into their thermodynamic properties and crystal growth behavior.
Rajabzadeh et al. (Tue,) studied this question.