Crystallographic Orientation Dependence of Dielectric Constant in Epitaxially Grown SrTiO3 Films

Abstract
Dielectric constants were compared between SrTiO3(STO) (100) and (110) films, which were epitaxially grown on Pt-deposited MgO (100) and MgO(110) single crystals, respectively. Epitaxial STO films with different orientation were prepared by rf sputtering. The relations between crystallographic orientation of the dielectric films and the substrates were confirmed to be (100) STO|| (100) Pt|| (100) MgO and (110) STO|| (110) Pt|| (110) MgO. The dielectric constant of the (100) oriented STO film was greater than that of the (110) oriented one. The orientation dependence of the dielectric constant is discussed from the viewpoint of thermodynamic phenomenology. It is clarified that the difference in interface energy between the dielectric and the electrode has an important role in determining the difference in the dielectric constant.