Signal performance of DC-SQUIDs with respect to YBCO thin film deposition rate

Abstract

a b s t r a c tThe signal performances of YBa 2 Cu 3 O 7−ı (YBCO) direct current superconducting quantum interference devices (DC-SQUIDs) have been investigated as a function of the thin film structure affected by the growth process. YBCO thin films of 200 nm thicknesses were deposited by DC magnetron sputtering using different deposition rates between 1.0 nm/min and 2.0 nm/min onto 24• bicrystal SrTiO 3 (STO) substrates. The thin film samples were subsequently analyzed by XRD and AFM in order to determine their crystalline structures and surface morphologies respectively. The 67 pH directly coupled DC-SQUIDs with 4 m-wide bicrystal Josephson junctions were fabricated, and characterized with respect to their device performances. The variations in the critical current (I c ), the voltage modulation depth ( V) and the noise performance of DC-SQUIDs were reported. The SQUIDs having relatively low deposition rate of 1.0 nm/min was observed to have larger voltage modulation depth as well as higher critical current than that of the samples having larger rate of 2.0 nm/min. The better noise performances were observed as the film deposition rate decreases. The results were associated with the thin film structure and the SQUID characteristics.

The effects of the post-annealing temperature on the growth mechanism of Bi2Sr2Ca1Cu2O8+ thin films produced on MgO (1 0 0) single crystal substrates by pulsed laser deposition (PLD)

“…Superconducting electronics devices require having high quality thin films, with high T C values and very smooth surfaces as well as in single crystalline form. In particular, the use of high quality high-T C thin films is important for device applications like SQUIDs [22,25], THz radiation sources [26], bolometers [23], intrinsic Josephson junctions [17,27], and other cryo-electronic devices.…”