Epitaxial growth of orientation-controlled KNbO3 crystal films on MgO using KTaxNb1−xO3 intermediate layer by metalorganic chemical vapor deposition

In this letter, we report a method to obtain an orientation-controlled (010) KNbO3 crystal film on (110) MgO substrate based on the epitaxial growth by the low-pressure metalorganic chemical vapor deposition. In order to control the orientation of the KNbO3 film, an intermediate layer of KTaxNb1−xO3 was used. In the case where the Ta/(Ta+Nb) ratio of the KTaxNb1−xO3 film was over 40%, we could obtain (010)-oriented epitaxial KNbO3 films. Furthermore, the surface morphology of the deposited film, the thickness of which was about 1 μm, was smooth at the Ta/(Ta+Nb) ratio of 60%. The measurement of the refractive index dispersion of the KNbO3 crystal film was also carried out.