A PHOTO-THERMOELECTRICAL YBCO-BISB THICK-FILM BOLOMETER

Among the thermoelectrical materials known so far, n-type semiconducti ng materials have a much higher thermoelectrical figure of merit (Z) t han do their p-type counterparts. This keeps the overall figure tow fo r a couple at all temperatures. At room temperature the best Z is abou t 10(-3) K-1 in the Bi-Sb-Te system. At liquid nitrogen temperatures, a suitable composition can deliver Z similar or equal to 10(-2) K-1 an d further improvement is possible with the application of a magnetic f ield. A combination of n-BiSb with a YBCO passive leg allows very high (alpha similar or equal to 200 mu V K-1) thermoelectrical power to be generated below T-c (similar or equal to 90 K) for incident radiation . The photo-thermoelectrical bolometer's design is such that this powe r drives the charge carriers around a circuit fabricated from YBCO-BiS b elements. The YBCO leg is inductively linked via a closely positione d copper film coil and connected to a remote ac bridge and an electron ic read-out system. A specific detectivity D of 2 x 10(11) W-1 cm Hz( 1/2) and a response time of the order of milliseconds, controlled basi cally by the inductive property of the superconducting element and its resistance in the mixed state, should be easily achieved. This paper presents an ab initio analysis of the new 50 mu m thick bolometer with a responsivity of about 100 V W-1.