HIGH TC SUPERCONDUCTING THIN FILMS FOR TRANSFER STANDARD RADIOMETERS.

HIGH TEMPERATURE SUPERCONDUCTING (HTSC) FILMS HAVE A LARGE POTENTIAL AS DETECTORS OF ELECTROMAGNETIC RADIATION. TO BE USEFUL FOR TRANSFER STANDARD RADIOMETERS, IT IS NECESSARY THAT THE HTSC FILM QUALITY SHOULD BE VERY HIGH, BOTH FROM THE VIEW POINTS OF STRUCTURE AND SUPERCONDUCTING PROPERTIES. A MAJOR TASK, IN ORDER TO ACHIEVE HIGH SENSITIVITY, FAST RESPONSE, LOW NOISE LEVELS, AND UNIFORM SPECTRAL RESPONSE OVER A BROAD WAVELENGTH RANGE IN THE DETECTOR, IS THAT THE HTSC FILM QUALITY BE MAINTAINED THROUGH ALL THE PROCESSING STEPS WHEN DEPOSITED ON VERY THIN AND LOW HEAT CAPACITY SUBSTRTES WITH INTEGRATED RADIATION ABSORBER AND RESISTIVE HEATERS. IN PHASE I OF THIS PROGRAM WE PROPOSE TO UNDERTAKE SUCH A TASK. USING A PULSED LASER DEPOSITION TECHNIQUE, WE WILL DEPOSTI HIGH QUALITY YBA2CU3O7 (YBCO) FILMS ON VERY THIN (25 UM) LOW HEAT CAPACITY SAPPHIRE SUBSTRATES WITH APPROPRIATE BUFFER LAYERS. THE FILM QUALITY WILL BE OPTIMIZED BY X-RAY DIFFRACTION. RUTHERFORD BACKSCATTERING, ION CHANNELING AND ELECTRICAL TRANSPORT MEASUREMENTS. WE WILL ALSO DEPOSIT AN INTEGRATED NI-CR THIN FILM RESISTIVE HEATER AND A BI THIN FILM RADIATION ABSORBER ON THE SAME SUBSTRATE. WE WILL MONITOR THE YBCO FILM PROPERTIES AT EACH OF THE DEPOSITION STEPS IN ORDER TO MAINTAIN A HIGH FILM QUALITY. WE WILL ALSO UNDERTAKE OPTICAL RESPONSE AND PRELIMINARY NOISE VOLTAGE MEASUREMENTS TO EVALUATE THE DETECTOR PERFORMANCE.