SIS DETECTOR IN THE 100 MICRON WAVELENGTH REGION FABRICATED WITH THIN FILM OF HIGH TC BI-CA-SR-CU-O SUPERCONDUCTOR

IN THE PROPOSED WORK, FEASIBILITY OF DEVELOPING AND CHARACTERIZING SIS DETECTOR, IN THE 100 MICRON WAVELENGTH REGION, FABRICATED BY LASER INDUCED DEPOSITION OF THIN FILM OF A NEW HIGH TC BI-CA-SR-CU-O SUPERCONDUCTOR (WITH TRANSITION TEMPERATURE OF 110 K), IS EXAMINED. THE DISCOVERY OF BCSCO MATERIAL IS VERY IMPORTANT BECAUSE WE NO LONGER NEED ANY RARE EARTH ELEMENT. THE DETECTION PRINCIPLEIS BASED ON THE FACT THAT INCIDENT FAR INFRARED RADIATION PRODUCES A VOLTAGE SHIFT ACROSS A WEAK-LINK TYPE SIS JOSEPHSON JUNCTION, WHICH CAN SERVE AS A USEFUL DETECTOR OUTPUT. IN THE PRESENT WORK, BULK SUPERCONDUCTOR SAMPLES OF BI-CA-SR-CU-O WILL BE PREPARED BY SOLID STATE REACTION METHOD. THIN SUPERCONDUCTING FILM OF 3-5 MICRON THICKNESS ON A SUITABLE SUBSTRATE (MGO) WILL BE PREPARED BY LASER INDUCED DEPOSITION TECHNIQUE USING PULSED EXCIMER LASER. TOFORM A WEAK LINK, A PART OF THE SUBSTRATE SURFACE WILL BE GROUND DOWN (OR ETCHED BY LASER) TO FORM A GROOVE OF ABOUT 5MICRON DEEP PRIOR TO THE DEPOSITION. FOR DETECTION, SUB-MM RADIATION FROM A BLACK BODY SOURCE WILL BE MODULATED AND GUIDED THROUGH A HOLLOW TUBE TO THE DETECTOR. IN PHASE I, DETECTOR PERFORMANCE IN TERMS OF RESPONSIVITY AND MINIMUM DETECTABLE POWER LEVEL (NEP) IN THE SPECTRAL REGION OF 100 MICRON WILL BE EVALUATED. THE RESPONSIVITY OF THE PROPOSED SIS DETECTOR IS ESTIMATED TO BE 10(4) V/W, WHICH IS SEVERAL ORDERS (4-5) OF MAGNITUDE HIGHER THAN THE PRESENTLY AVAILABLE DETECTORS IN THE 100 MICRON WAVELENGTH REGION. RESPONSE TIME OF THE DETECTOR WILL BE INVESTIGATION IN PHASE II.