Growth and piezoelectric properties of amorphous and crystalline (K1−xNax)NbO3− based thin films |
Jong-Un Woo1, Sun-Woo Kim2, Dae-Su Kim2, In-Su Kim2, Ho-Sung Shin2, Sahn Nahm1,2 |
1KU-KIST Graduate School of Converging Science and Technology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea 2Department of Material Science and Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea |
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Received: November 4, 2020; Revised: November 28, 2020 Accepted: January 21, 2021. Published online: May 31, 2021. |
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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. |
Key words:
K0.5Na0.5NbO3 · Thin fi lms · Ferroelectrics · Piezoelectrics · Lead-free materials |
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