Large Transverse Piezoelectricity in Highly (001)-Oriented PZT Thick Films on Titanium Substrates

Area of Science:

• Materials Science
• Thin Film Technology
• Piezoelectric Materials

Background:

• Integrating lead zirconate titanate (PZT) on flexible metallic substrates for piezoelectric devices is crucial but hindered by interfacial diffusion and oxidation.
• Achieving highly textured PZT films on reactive substrates like titanium presents significant challenges.

Purpose of the Study:

• To develop a method for depositing highly textured PZT thick films on titanium substrates for flexible piezoelectric applications.
• To overcome interfacial degradation and achieve superior piezoelectric properties on metallic substrates.

Main Methods:

• Deposition of ~1.3 μm PZT thick films on titanium using radio-frequency magnetron sputtering at 400 °C.
• Introduction of a conductive LaNiO3 (LNO) buffer layer to promote perovskite nucleation and prevent interfacial issues.
• Rapid thermal processing at 640 °C for 2.5 min to crystallize the PZT films.

Main Results:

• PZT films on LNO/Pt/Ti substrates exhibited strong (001) preferred orientation and dense microstructure.
• Achieved high remnant polarization (Pr ~61 μC cm⁻²) and low coercive field (Ec ~56 kV cm⁻¹).
• Demonstrated a transverse piezoelectric coefficient (e31,f) of ~-6.7 C/m² in patterned cantilevers, outperforming existing films on Ti.

Conclusions:

• Controlled nucleation via an LNO buffer and rapid thermal crystallization enable highly textured PZT films on reactive metallic substrates.
• This approach provides a viable route for fabricating high-performance flexible piezoelectric microelectromechanical systems (MEMS) devices.