First-principle study on the effect of point defects on the mechanical properties, thermal conductivity, and optical properties of wurtzite AlN

Defects (VAl/VN) and unintentional impurities (C/O/Si/Hi) will inevitably exist during the preparation of AlN by metal-organic chemical vapor deposition and physical vapor transport. In particular, Hi is very difficult to remove in a vacuum environment. First-principle calculations were used to research the mechanical properties, thermal conductivity, and optical properties of AlN and its defect-containing systems. Results showed that the deformation resistance of Al36SiN35 and Al35ON36 systems was relatively poor, and the hardness was relatively small. When the impurity C or O located in the N position, the effect on the anisotropy of AlN was relatively large. O impurities and Al vacancies had relatively large effects on the thermal conductivity of AlN lattice. When the O impurity was located at the N position and the Si impurity was located at the Al position, the influence on the optical properties of AlN was relatively large, which would help improve the polarization ability, refractive index, reflectivity, and absorption of the visible light of AlN.