Giant Piezoelectric Properties of ZnO Film Doped with Acceptor-Donor Ionic Pair

Piezoelectric thin film materials are high energy density materials that scale very favorably upon miniaturization and that has led to an ever-growing interest for MEMS applications. Thus extensive investigation of lead-free piezoelectric has been triggered out of environmental awareness. Here, a concrete lead-free paradigm is presented, Zn1-2x(FexLix)O thin films, which exhibits a splendid d33* value (~415 pm/V) and electrostrain (~0.68%) after thermal-electric treatment in the co-doped film with the x value of 0.06. It is considered that the local lattice distortion generated by preferential distributed Fe3+-Li+ ionic pairs is responsible for the outstanding piezoelectric properties and obvious ferroelectricity response. The defect engineering strategy presented in this work open a new development window for obtaining excellent piezoelectricity in a wide range of binary metal oxide systems and have profound implications for the potential utilization of lead-free piezoelectrics in microelectromechanical systems and surface acoustic wave devices.