Single-chamber, i n s i t u processing of superconducting YBa2Cu3O7−δ thin films on stainless steel with yttria-stabilized zirconia buffer layer

Abstract

Single-chamber in situ laser processing of high-Tc YBa2Cu3O7−δ film on stainless steel (302) substrates with yttria-stabilized zirconia (YSZ) buffer layers, has been carried out using a multitarget deposition system. YSZ and YBa2Cu3O7−δ films were deposited sequentially by KrF excimer laser (λ=248 nm) at substrate temperature of 650 °C. The films were characterized by x-ray diffraction, four point probe ac electrical resistivity, scanning electron microscopy and Auger electron spectroscopy (AES) techniques. Due to the matching of the thermal expansion coefficient of YSZ with stainless steel and its diffusion barrier characteristics, good quality high-Tc films have been grown on stainless steel substrates with superconducting transition temperature, Tc (onset), of 92 K and Tco (zero resistivity temperature) of 84 K. AES depth profiling indicated little interdiffusion of Fe across the interface of YSZ and stainless steel. A laser evaporation method was used for patterning the YBa2Cu3O7−δ films and critical current density, Jc, was measured to be ∼5×104 Acm−2 at 40 K. It was observed that the zero resistivity temperature significantly changed with the variation of buffer layer thickness, buffer layer processing temperature, and ambient oxygen partial pressure during the deposition of YBa2Cu3O7−δ.