Heteroepitaxial growth of Sr1.8Ca0.2NaNb5O15/Li0.25Ni0.75O/MgO by pulsed laser deposition

• Smoother surface and waveguide quality were achieved by two-step method.
• The Li0.25Ni0.75O serves as ideal bottom electrode and epitaxial buffer layer.
• The couple prism technique is a useful sensitive surface probe.

High quality Sr1.8Ca0.2NaNb5O15/Li0.25Ni0.75O (SCNN/LNO) epitaxial heterostructures on (100) MgO substrates have been fabricated by pulsed laser deposition. X-ray diffraction analysis confirmed that the bilayer films possess an (001) orientation normal to the substrate surface. The LNO layer with smooth surface and good semiconductor behavior served as an ideal bottom electrode in the metal-insulator–semiconductor structure and an excellent template for epitaxial growth of SCNN thin film. Our results show that SCNN films with smoother surface, better (001) epitaxial orientation and better waveguide quality can be obtained by controlling the morphology of the LNO layer in a two-step deposition process.