New Type of Nitrides with High Electrical and Thermal Conductivities**Supported by the National Natural Science Foundation of China under Grant Nos 51532010, 91422303, 51672306 and 51772322, the National Key Research and Development Program of China under Grant No 2016YFA0300604, the Beijing Municipal Science & Technology Commission under Grant No Z161100002116018, and the Strategic Priority Research Program of the Chinese Academy

Abstract

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 SiN4 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 × 105 S/cm) and a high thermal conductivity (371 W/m⋅K) comparable to copper. The validity is tested by isostructural AlN4 and SiC4. It is demonstrated that the nitrogen dimers can supply a high density of delocalized electrons in this new type of nitrides.