Perfect Uniaxial Growth of Dion−Jacobson Perovskite RbLaNb2O7 Thin Films under Pulsed Photothermal Gradient Heating

Abstract

A new straightforward process for fabricating perfect uniaxial oriented Dion−Jacobson perovskite RbLaNb2O7 thin films by excimer-laser-assisted metal organic deposition (ELAMOD) has been investigated. The oriented crystal growth occurred only as a result of excimer laser irradiation in air at 400 °C, after deposition of metal organic solution and preheating at 400 °C. The obtained RbLaNb2O7 thin film exhibited perfect (010)-oriented growth on a silica glass substrate. We discuss the uniaxial growth mechanism in terms of spatial heating by comparing the gradient temperature distribution near the film surface under photothermal heating in the ELAMOD process and the temperature distribution under macroscopic homogeneous heating in the conventional MOD process. Under gradient heating by excimer laser irradiation, the first nucleation preferentially occurred at the film surface with (010)-layered structural ordering to reduce the crystal surface energy. Then, the film was epitaxially grown downward from the fi...