Enhancing the structure and piezoelectric properties of AlN/Mo multilayers via insertion of an AlN seed layer

Abstract

In this work, systematic investigations were conducted to explore the effects and mechanisms of sputtering conditions on the structure and piezoelectric properties of aluminum nitride (AlN) films. Specifically, the contribution of a high-temperature-grown AlN seed layer to the performance of piezoelectric AlN films with molybdenum (Mo) electrodes was demonstrated. Compared with the unseeded AlN/Mo structure, the seeded system exhibited superior crystallization quality, reduced internal stress, and well-maintained surface morphology. Piezoresponse force microscopy measurements revealed a significant enhancement in the piezoelectric coefficient (d33) from 0.7 to 6.2 pm/V after incorporating the AlN seed layer. These results indicate that the high-temperature-grown AlN seed layer simultaneously improves both the structural integrity and piezoelectric performance of AlN films on Mo electrodes, providing a novel strategy for the development of high-performance AlN-based microelectromechanical system devices.