Growth and characterization of epitaxial Ba(Co,Zn)1/3Nb2/3O3 thin films

• Epitaxial Ba(Co,Zn)1/3Nb2/3O3 thin films were grown on MgO substrates above 500 °C using Pulsed Laser Deposition.
• Enhanced oxygen pressure and in-situ annealing during the growth were found to improve the film quality.
• The optical properties were studied from UV–vis absorption and transmission measurements.
• The film shows a high dielectric constant of ~34, comparable to that of the bulk.

Pulsed Laser Deposition has been used to synthesize Ba(Co,Zn)1/3Nb2/3O3 (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 χminχmin 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.