First-Principles Study on Elastic Properties of AlN

Structural and elastic properties of AlN are investigated by using First-principles. Both of wurtzite and zinc-blende structures are investigated, respectively. The bulk moduli of the wurtzite structure and zinc blende AlN are 194.2GPa and 187GPa, which obtained by the elastic stiffness constants respectively. Shear moduli are 136GPa and 124GPa. Young's moduli are 331GPa and 305GPa. Poisson's ratio and Pugh criterion suggests that both of them are brittle material. The brittleness of wurtzite AlN is higher than that of zinc-blende AlN. The elastic anisotropy of the bulk moduli and shear moduli were discussed. Three-dimensional anisotropic of the young's modulus were analyzed.