Preparation of Ba-Y-Cu-O Films by Laser Ablation

Abstract

Superconducting Ba₂YCu₃O _x films were prepared on various kinds of substrate by ArF excimer laser ablation, mainly in O₂ ambient gas, followed by low temperature (490°C) O₂ annealing. In particular, the film (thickness 1.7 μ,m) on crystalline Si without a buffer layer exhibited a zero resistance at 82 K. Furthermore, the excimer laser irradiation on the growing film surface was found to improve superconductive properties and surface morphology of the films prepared at a relatively low substrate temperature. This improvement is likely to be brought about mainly by the enhancement of film crystallization. Use of an N₂O ambient gas instead of O₂ was found to enhance the c-axis orientation of the films on the Si. Oxygen atoms produced from N₂O appear to play an important role to reduce the crystallization temperature.