Synthesis and characterization of single crystalline REBa2Cu3O7-y thin film grown by tri-phase epitaxy

We report on the successful fabrication of single crystalline thin films of REBa₂Cu₃O_7-y (RE123, RE: rare earth elements) using a novel process of Tri-Phase Epitaxy. This method is based on the application of pulsed laser deposition (PLD) under appropriate compositions and conditions predetermined from the relevant thermodynamic phase diagram. Prior to the growth of the film, a liquid phase film (near-eutectic composition of BaO-CuO) is intentionally formed. The RE123 single crystalline thin film is grown at the liquid-solid interface. The consumed RE123 in the liquid layer is compensated by the laser-ablated vapor and the composition of the liquid phase is kept constant. Thermodynamic equilibrium can be maintained at the liquid-solid film boundary while preserving the benefit of intrinsic stoichiometry control offered by the PLD technique. Atomically smooth film surface and single crystalline nature of film was verified by combined characterization methods of x-ray diffraction, atomic force microscopy and transmission electron microscopy.