A Review of the Recent Applications of Aluminum Nitride-Based Piezoelectric Devices

Abstract

Piezoelectric materials have attracted considerable attention over the last two decades because many technologies utilize their core properties of piezoelectric materials. Previous applications consisted of bulk structures; however, a shift towards better performance and a more simplified and compatible fabrication method are required. Aluminum nitride (AlN) is a material that fits these criteria; it has a non-centrosymmetric crystal structure with a polarized c-axis and exhibits piezoelectric properties. Furthermore, it has an added benefit as the fabrication process of AIN is compatible with complementary metal-oxide semiconductor technology. This has led to a rapid increase in the adoption and interest in AlN-based devices. In this review, the crystal structure of AlN and its piezoelectric properties are compared with those of aluminum scandium nitride. Subsequently, functional devices such as consumer-based devices, telecommunication-based devices, industrial-related applications, and medical applications are presented. Finally, a summary and discussion of the future AlN research are presented.