Deposition and Evaluation of YBCO Thin Films by the Visible Light Pulsed Laser Ablation Method

Abstract

Thin film of YBa₂Cu₃O_7-δ (YBCO) was deposited on a MgO substrate by the visible light (532nm) pulsed laser ablation method using a Nd:YAG laser. The purpose of this study is to find out the optimum composition of target and to improve the quality of thin films by introducing oxygen radicals. Thin film deposited in O₂ gas at substrate temperature of 600°C and thermally annealed at 925°C in the air using a target with mol ratio of 1:2:4 of Y, Ba, and Cu (1:2:4 target) changed to the super conducting state at 69K, which was the highest among those of thin films deposited using targets with different compositions. Thin film deposited in O₂ gas including oxygen radicals produced by the oxygen plasma using a 1:2:4 target changed to the superconducting state at 75K. Resistance decreased rapidly with decreasing temperature near superconducting transition temperature. Thin film deposited in O₂ gas including oxygen radicals at 730°C using a 1:2:4 target without thermal annealing changed to the superconducting state at 50K.