New Type of Nitrides with High Electrical and Thermal Conductivities

The nitrogen dimer as both a fundamental building unit in designing a new type of nitrides, and a material gene associated with high electrical and thermal conductivities is investigated by first principles calculations. The results indicate that the predicted SiN_4 is structurally stable and reasonably energy-favored with a striking feature in its band structure that exhibits free electron-like energy dispersions. It possesses a high electrical conductivity (5.07\times10^5 S/cm) and a high thermal conductivity (371 W/m\cdotK) comparable to copper. The validity is tested by isostructural AlN_4 and SiC_4. It is demonstrated that the nitrogen dimers can supply a high density of delocalized electrons in this new type of nitrides.