First-principle studies on the influence of anisotropic pressure on the physical properties of aluminum nitride

Abstract

In this work, we performed extensive first-principle studies to discuss the effect of uniaxial and biaxial mechanical pressure on the structural and physical properties of AlN piezoelectric material, including the longitudinal elastic constant (C33), piezoelectric constant (e33), static dielectric constant (ε33), and mass density (ρ). In particular, we give the relationship between the paramters mentioned above and the longitudinal acoustic wave velocity (V) under anisotropic pressure. Our results show that the applied uniaxial or biaxial pressure in the basal plane has a more obvious influence on physical properties of AlN than the uniaxial pressure along hexagonal axis. The pressure-induced variations of C33, e33 and ρ significantly change the V value, whereas the effect of ε33 on V is negligible. Our theoretical results provide useful information for the performance predictions of electro-acoustic mechanics sensors, such as FBAR mechanical sensors, based on the intrinsic properties of piezoelectric materials.