Epitaxial layered cobaltite NaxCoO2 thin films grown on planar and vicinal cut substrates

► Epitaxial layered cobaltite Na0.50.7CoO2 thin film grown on different planar substrates. ► Annealing at high temperature results in good crystalline quality, large layered structure grain, much smoother film surface and low resistivity. ► The interface between NaxCoO2 film and substrate and the one unit height of film have been observed by HRTEM. ► c-Axis orientation epitaxial growth only occurred when STO substrate with tilted angle θ≤5°.