(1 0 1) and (0 0 2) oriented AlN thin films deposited by sputtering

Abstract

Reactively sputtered aluminum nitride (AlN) is a piezoelectric material, largely used for technological applications, ranging from sensors to energy harvesting. The structural properties of AlN are crucial for its integration in piezoelectric devices. The preferential orientation of the film discriminates its applicability in devices, where the excitation of the longitudinal rather than the shear mode is required. In order to tune the film crystallographic orientation, a fine control of the sputtering parameters is required. In this paper, a structural switch, from (002) to (101) preferential orientation was obtained by increasing the total pressure in the deposition chamber with the only use of the throttle valve, while keeping constant all the other deposition parameters. This structural change was interpreted on the basis of the growth kinetics, which explains how deposition parameters control the energy of the species impinging on the substrate.