HIGHLY SENSITIVE FAR INFRARED SENSOR FABRICATED WITH HIGH TC TL-BA-CA-CU-O SUPERCONDUCTOR THIN FILMS

IN THE PROPOSED PROGRAM, FOR THE FIRST TIME, FEASIBILITY OF DEVELOPING AND CHARACTERIZING HIGHLY SENSITIVE BOLOMETER IN THE 10-100 FM WAVELENGTH REGION USING HIGH TEMPERATURE T1-BA-CA-CU-OSUPERCONDUCTING THIN FILM, IS EXAMINED. THESE MATERIALS BECAUSE OF THE LOW BAND GAP ENERGY (\ W 25 MEV) AND SHARP TRANSITION TEMPERATURE, THEY ARE INHERENTLY CAPABLE OF DETECTING RADIATION OVER A WIDE WAVELENGTH RANGE DOWN TO 100 FM WITH A HIGH SENSITIVITY. FURTHERMORE BECAUSEOF TC W 125 K, THEY CAN BE OPERATED EFFICIENTLY AT LIQUID NITROGEN TEMPERATURE. RECENTLY, IN A PRELIMINARY EXPERIMENT, WE HAVE OBSERVED A HIGHLY SENSITIVE (10 V/W) BOLOMETRIC RESPONSE WITH YBCO FILMS SUBJECTEDTO 0.5 FM LASER RADIATION AT OR ABOVE THE TRANSITION TEMPERATURE. THIS WORK WAS THE WORLD'S FIRST DEMONSTRATION OF BOTH EQUILIBRIUM AND NON-EQUILIBRIUM DETECTION MADE IN THIS NEW CLASS OF HIGH TEMPERATURE SUPERCONDUCTOR. IN THE PROPOSED WORK, EXTREMELY SMOOTH AND OPTICALLY SEMI-TRANSPARENT T1-BA-CA-CU-O SUPERCONDUCTING FILMS AS THIN AS 80 NM DEPOSITED ON SUITABLE SUBSTRATES BY PLASMA ASSISTED LASER DEPOSITION TECHNIQUE WILL BE PURCHASED. IN ORDER TO IMPROVE THE RESPONSIVITY OF THE DETECTOR, THESE FILMS WILL BE PATTERNED IN A MEANDER SHAPE BY LASER INDUCED ETCHING PROCESS. FOR INFRARED DETECTION, A 10.6 FM CO2 LASER SOURCE WILL BE MODULATED AND GUIDED THROUGH AN OPTICAL FIBER TO THE DETECTOR. IN PHASE I, THERMAL RESPONSE OF THESE DETECTORS AT 10.6 FM, TEMPERATURE AND WAVELENGTH (10-100 FM) DEPENDENCE OF THE RESPONSE WILL BE STUDIED. THE RESPONSIVITY OF THE DETECTOR IS ESTIMATED TO BE TEN TO THE POWER FOUR VOLTS PER WATT WHICH IS SEVERAL ORDERS OF MAGNITUDE HIGHER THAN PRESENTLY AVAILABLE ANY KIND OF DETECTORS OPERATING AT LIQUID NITROGEN TEMPERATURE IN THE SUB-MM REGION. ANTICIPATED BENEFITS/POTENTIAL COMMERCIAL APPLICATIONS - THE POTENTIAL COMMERCIAL APPLICATIONS OF THESE DEVICES ARE IN THE AREA OF SUB-MM SPECTROMETER, RADIOMETER, NIGHT VISION, AND OPTICAL COMMUNICATIONS.