THE CRITICAL-CURRENT DENSITY DISTRIBUTION IN A TLBACACUO THIN-FILM RING-RESONATOR

Low temperature scanning electron microscopy (LTSEM) offers the possib ility for spatially resolved investigation of superconducting properti es of the integrated microwave devices made of high T-c thin films. In this paper the LTSEM has been used to study the spatial distribution of the critical current density J(c) in a millimetre-wave microstripli ne ring resonator made of TlBaCaCuO thin film. The resonator was patte rned by standard photolithography and wet etching on a TlBaCaCuO thin film fabricated by DC sputtering on a LaAlO3 substrate with post-annea ling. The experimental result shows that the inhomogeneity of the J(c) distribution in the device is not very serious. The maximum local cri tical current density is less than 1.5 times the minimum local critica l current density. It seems to us that the J(c) distribution in the ri ng area is determined by the inhomogeneity of the superconducting prop erties of the thin film and is not influenced by the geometrical patte rn of the device.