Structural and electrical properties of KNbO3 thin film grown on a Pt/Ti/SiO2/Si substrate using the RF magnetron sputtering method

A homogeneous KNbO3 (MN) thin film was grown on a Pt/Ti/SiO2/Si substrate using the RF sputtering method. A K2.88Nb5O15 secondary phase was formed in the KN film when the deposition and the annealing temperatures were greater than room temperature (RT) and 800 degrees C, respectively, owing to the evaporation of K2O. On the other hand, KNb3O8 and K3Nb5.45O15 secondary phases were formed in the KN films when the annealing temperature was less than 800 C or the annealing time at 800 degrees C was shorter than 90 min. A homogeneous KN thin film was formed when it was deposited at RT and subsequently annealed at 800 degrees C for 90 min under the K2O atmosphere. This KN film exhibits a relative permittivity of 884 with a dissipation factor of 6.71% at 100 kHz. The leakage current density of 1.06 x 10(-6) A/cm(2) at 0.1 MV/cm and a breakdown field of 1.5 MV/cm were observed from this film. This film showed a saturation polarization of 21.9 mu C/cm(2), with a remnant polarization of 8.3 mu C/cm(2), and a piezoelectric strain constant of 125 pm/V. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.