Abstract
Three Y 1 Ba 2 Cu 3 O 7-δ superconducting thin films with 20%, 60%, and 100% coverage of precipitates were fabricated into microbndges of 25×650 μm 2 by a conventional photolithography method. These microbridges exhibit a T co (R=0) from 83.6 to 87.2 K and a transition width of about 1.8 K. These also have (dR/dt) max values of about 71-78 Ω/K. We find that the fewer the precipitates on the film, the better the thermal conduction, and a larger responsivity (S) can be achieved The best responsivity of 783 V/W measured at l b =8 mA, T op =86.8 K, and f=2 Hz for various wavelengths of light sources is obtained from the film with 20% precipitation. The photoresponse signals decay exponentially with the precipitation coverages, which indicates that these precipitates behave as thermal resistance layers that smooth out the ac incident signal, suppress the rise in microbridge temperature, and result in a smaller photoresponse signal for the bolometer. © 1996 American Institute of Physics.