First-principles calculations have been carried to study the structural and electronic properties of the series of α-silicon carbon nitride crystals which have been successfully synthesized and demonstrate interesting mechanical, electronic, optical properties. The bulk modulus values of the SiCN structures have been observed to progressively increase up as more C atoms substituted for Si atoms in the crystal due to strong covalent CN bonds compared to SiN bonds. The band structure calculations indicate that the electronic properties of the α-SiCN crystals are closer to α-Si3N4 than to α-C3N4. In addition, to improve the underestimation of local density approximation, we implement the generalized density functional scheme to correct the band gap values for SiCN crystals. The size of the band gap for α-Si2CN4 after gap opening shows a value of 3.82 eV which demonstrates a good approximation with that of the Si-rich SiCN crystals measured by the piezoreflectance spectroscopy, ranging from 3.81 to 4.66 eV.
Diamond and Related Materials 13(4-8), pp.1158-1165