Growth and piezoelectric properties of amorphous and crystalline (K1−xNax)NbO3−based thin films

Abstract

(K1−xNax)NbO3 (KNN)-based piezoelectric thin films have been extensively studied for application in micro-electromechanical systems. However, growing homogenous crystalline (K1−xNax)NbO3 (CKNN) films with good piezoelectric properties is difficult because Na2O and K2O evaporate during the growth process at high temperatures. Recently, amorphous (K1−xNax)NbO3 (AKNN) films containing KNN nanocrystals with good piezoelectric properties have been fabricated at low temperatures. Furthermore, [001]-oriented crystalline (K1−xNax)NbO3 (OCKNN) films with excellent piezoelectric properties have been grown at low temperatures (≤ 350 °C) using a metal-oxide nanosheet seed layer. This novel method is excellent for the growth of homogeneous KNN thin films. These films were deposited on a polymer substrate; thus, they can be utilized in future flexible electronic devices. In this study, the structural and piezoelectric properties of AKNN- and CKNN-based films fabricated at high temperatures, along with the growth process and application of OCKNN-based thin films at low temperatures, are reviewed.