Molecular Dynamics Simulation of Stress in AlN Thin Films on Sapphire Substrate

In this article, we study the stress and defects of AlN on sapphire substrate by molecular dynamics. The temperatures and film thickness were varied to investigate the effect. We find that the mixing of film atoms with substrate atoms could be observed. As the temperature increases, the mixing of film atoms with the substrate atoms becomes more obvious. This is due to the increased kinetic energy of atoms as the temperature increases. Moreover, the fluctuation range of the average mean biaxial stress and the average normal stress mainly occur at the interface between AlN film and sapphire substrate. This is understandable because the lattice mismatch exits between AlN film and sapphire substrate, which inevitably leads to atom mismatch and involve defects and stress.