Epitaxial layered cobaltite Na xCoO 2 thin films grown on planar and vicinal cut substrates

Abstract

Epitaxial layered cobaltite Na 0.5–0.7CoO 2 thin films have been grown on planar SrTiO 3 (1 0 0), SrTiO 3 (1 1 0), LaAlO 3 (1 0 0) and α-Al 2O 3 (0 0 0 1) substrates successfully by pulse laser deposition. The annealing temperature to influence of the crystal structure, surface morphology and electrical transport properties of Na x CoO 2 thin films has been investigated. The layered structure of Na x CoO 2 film and the interface between the film and substrate have been observed clearly by high resolution transmission electron microscopy. Vicinal cut SrTiO 3 (1 0 0) substrates with the c-axis tilted angle θ 3–10° have been used to grow Na x CoO 2 thin films, which reveals that the c-axis orientation epitaxial growth on vicinal cut SrTiO 3 (1 0 0) substrates only occurred when tilted angle θ≤5°.