Possible enhancement in bolometric response using free-standing film of YBa2Cu3Ox

摘要

Improvement of the sensitivity in infrared detectors made of high T$-c$/ superconducting films is discussed. Usually these films are grown on a substrate which results in reduced sensitivity due to additional heat capacity of the substrate. A five-fold increase of the noise equivalent power is calculated if free-standing superconducting films are used. A new technique for preparation of thin films of YBa$-2$/Cu$-3$/O$-x$/ without a substrate is also described. The film material is deposited by pulsed laser ablation on a thin carbon film. When the film is annealed in situ in oxygen, the carbon burns off, leaving a free-standing film. The film area can be large as 10$MUL@10 mm$+2$/ and less than one-half micron thick. They have the correct stoichiometry, the orthorhombic phase and an onset temperature of about 85 K.