Growth and characterization of epitaxial Ba(Co,Zn)_1/3Nb _2/3O₃ thin films

Pulsed Laser Deposition has been used to synthesize Ba(Co,Zn) _1/3Nb_2/3O₃ (BCZN) dielectric thin films on MgO (001) substrates. The BCZN films are epitaxial and have an orientation of (001) // MgO (001) and (100) // MgO (100) when deposited at substrate temperatures above 500 C. The film grown at 800 C has the best structural quality, with an X-ray diffraction rocking curve width of ∼0.5 and a channeling Rutherford Backscattering Spectrometry ^χmin value of 8.8%. The surface roughness decreases monotonically with increasing substrate temperature, with a ∼3 nm root mean square roughness value for the films deposited at 700 C. Optical transmission measurements indicate a strong direct transition at ∼4 eV and a refractive index of 2.0 in the visible range. A low-frequency dielectric constant of 34 was measured using a planar interdigital contact structure. The resistivity of the film is 3×10¹⁰ Ω cm at room temperature and has a thermal activation energy of 0.66 eV.