SUPERCONDUCTING NIOBIUM INFRARED THERMAL DETECTORS AND CIRCUITS ON BACK-ETCHED SUBSTRATES

We report on highly sensitive thermal infrared detectors, the result of combining the two technologies of superconducting low-T-c thin-film electronics and back-etched or "micromachined" substrates. We have fabricated functioning detectors consisting of a thin-film niobium Josephson junction thermometer and infrared-absorbing panel, integrated together with a dc SQUID amplifier on a single back etched silicon substrate. A detector made with one of two fabricated back-etched geometries has a calculated thermal conductance of 1 x 10(-7) W/K at 4.2 K. On another device, a measured value of 9x was obtained for the amplification of the thermometer responsivity by the integrated dc SQUID. Prospects are discussed for operating similar arrays at higher and lower temperatures than 4.2 K.