Abstract

Ferroelectric phase transitions and the structure of KNbO3 nanometer-thick films deposited by Metal-organic chemical-vapor deposition technique on a MgO(100) substrate are studied. Thin KNbO3 films of the average thickness from 20 to 150 nm possess a grainlike structure with a lateral grain size of about 250 nm. Such films reveal ferroelectric properties similar to KNbO3 single crystal. Temperature dependencies of optical second harmonic generation intensity show that the Curie temperature T-C of the nanometer-thick KNbO3 films is about 30 degrees C lower than the T-C of KNbO3 single crystal, which is attributed to size effects in KNbO3 nanograins. (c) 2006 American Institute of Physics.