Heteroepitaxial Growth of Perovskite CaTaO2N Thin Films by Nitrogen Plasma-Assisted Pulsed Laser Deposition

We demonstrated heteroepitaxial growth of perovskite CaTaO2N on SrTiO3 (100) substrates by using nitrogen plasma assisted pulsed laser deposition (NPA-PLD). The CaTaO2N films grew coherently on SrTiO3 substrates, showing a layer-by-layer growth mode in the initial stages. The obtained films possessed high crystallinity, a sharp film/substrate interface, and flat surfaces. Impedance measurements revealed that CaTaO2N has a much smaller dielectric constant than those of SrTaO2N or BaTaO2N. These results indicate that heteroepitaxial growth by NPA-PLD is a promising approach for preparing high-quality perovskite oxynitride single crystals, which are desirable for investigation of electrical properties of perovskite oxynitrides.