title: Optical Properties of Ferroelectric Epitaxial K0.5Na0.5NbO3 Films in Visible to Ultraviolet Range.
abstract: The complex index of refraction in the spectral range of 0.74 to 4.5 eV is studied by variable-angle spectroscopic ellipsometry in ferroelectric K0.5Na0.5NbO3 films. The 20-nm-thick cube-on-cube-type epitaxial films are grown on SrTiO3(001) and DyScO3(011) single-crystal substrates. The films are transparent and exhibit a significant difference between refractive indices Δn = 0.5 at photon energies below 3 eV. The energies of optical transitions are in the range of 3.15-4.30 eV and differ by 0.2-0.3 eV in these films. The observed behavior is discussed in terms of lattice strain and strain-induced ferroelectric polarization in epitaxial perovskite oxide films.
authors.affiliation: Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221.|Czech Technical University, Technicka 2, Prague 6, Czech Republic, 166 27.
authors.forename: E
authors.identifier: http://orcid.org/0000-0002-4422-8045
authors.initials: E
authors.lastname: Chernova
authors.affiliation: Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221.
authors.forename: O
authors.initials: O
authors.lastname: Pacherova
authors.affiliation: Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221.
authors.forename: T
authors.initials: T
authors.lastname: Kocourek
authors.affiliation: Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221.
authors.forename: M
authors.initials: M
authors.lastname: Jelinek
authors.affiliation: Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221.
authors.forename: A
authors.initials: A
authors.lastname: Dejneka
authors.affiliation: Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221.|Microelectronics and Materials Physics Laboratories, University of Oulu, P. O. Box 4500, FI-90014 Oulun yliopisto, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Tyunina
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D012031:Refractometry; D013057:Spectrum Analysis; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D009930:Organic Chemicals; D010087:Oxides; C059910:perovskite; D014025:Titanium