Preparation of YBa₂Cu₃O_7−δ thin film by laser-assisted metal-organic chemical vapor deposition using highly volatile fluorocarbon-based Ba source

Abstract

Superconducting oxide films of YBa₂Cu₃O_7-δ (YBCO) were produced on magnesia (MgO) single crystalline substrates (100) by laser-assisted metal-organic chemical vapor deposition. The highly volatile Ba(hfa)2 • tetraglyme was used as a Ba source metal-organic material. Smoother surface YBCO film was obtained with KrF laser irradiation than without. However, KrF laser irradiation does not lower the temperature for formation of YBCO(123) phase. YBCO film prepared at 750 °C on the MgO substrate showed a T_c(R = 0) of 69 K, and that prepared with KrF laser irradiation was 85 K. When water was added to the reaction chamber, barium fluoride was reduced and the YBCO formation was detected at a temperature of 650 °C and higher. YBCO film prepared at the temperature of 700 °C for 40 min without KrF laser irradiation behaves as a semiconductor, and one prepared with laser irradiation showed a T_c(R = 0) of 78 K.