Development and Integration of Next-Generation Piezoelectric Materials via Advanced Sputtering Techniques for Micro/Nano Systems

Miniaturized piezoelectric materials are driving a new generation of compact, energy-efficient technologies, enabling functionalities in a wide range of applications—from sensors and actuators to communication systems and energy harvesters. These materials play a pivotal role across multiple sectors, including health, consumer electronics, automotive systems, aerospace engineering, and next-generation wireless technologies.

The synthesis of high-performance piezoelectric materials that are fully compatible with standard CMOS fabrication workflows continues to represent a major challenge in materials science. Aluminum nitride (AlN) has consequently attracted significant attention as a promising alternative, due to its intrinsic CMOS compatibility, high thermal conductivity, chemical stability, and mechanical robustness. However, the intrinsic piezoelectric response of undoped AlN is considerably lower than that of conventional materials like PZT, which significantly limits its suitability for advanced applications requiring strong electromechanical coupling and high sensitivity. Recent studies have demonstrated that doping AlN with scandium (Sc) or other rare-earth elements such as yttrium (Y) and ytterbium (Yb) can enhance its piezoelectric coefficient by up to 500%. Despite these promising results, the industrial integration of rare-earth-doped AlN remains constrained by two key issues: the high cost and limited availability of rare-earth sputtering targets, and the difficulty of achieving compositionally stable, high-quality films at elevated dopant concentrations. There is growing interest in identifying alternative dopants that are both functionally effective and industrially scalable. A particularly promising approach involves the use of earth-abundant transition metals such as titanium (Ti), zirconium (Zr), and hafnium (Hf), which have demonstrated comparable, or even superior, enhancements in piezoelectric performance. In addition to their favourable electromechanical properties, these dopants offer key advantages in terms of cost-efficiency, material abundance, and compatibility with existing fabrication processes, positioning them as attractive candidates for next-generation piezoelectric thin film technologies.

This PhD project will leverage a new state-of-the-art sputtering system for advanced thin film deposition, to explore and optimize the growth of novel piezoelectric materials. The tool provides unprecedented control over deposition parameters enabling the exploration of complex material phase spaces.

The aim of this doctoral research is to (1) develop a robust sputtering process for one or more next-generation piezoelectric materials, (2) understand the relationship between process conditions, microstructure, and functional properties, and (3) demonstrate integration into prototype MEMS devices (e.g., resonators, sensors, actuators). The project will involve close interaction between thin film process development, structural and functional characterization (XRD, SEM, AFM, PFM, impedance spectroscopy), and electromechanical testing, integration process of the Micro/Nano systems.