TWO-DIMENSIONAL LONG WAVELENGTH BOLOMETER ARRAYS FOR ASTRONOMY APPLICATIONS

RESARCHERS ARE DEVELOPING A NOVEL AND INNOVATIVE METHOD TO FABRICATE LARGE-AREA, LONG WAVELENGTH INFRARED (LWIR) DETECTOR ARRAYS THAT CAN BE OPERATED AT ROOM AS WELL AS CRYOGENIC TEMPERATURES. THE TECHNIQUE IS USING ESTABLISHED TECHNOLOGIES OF MICRO-MACHINING AND MICROELECTRONIC PROCESSING OF SILICON (SI) WAFERS FOR FABRICATING MONOLITHIC ARRAYS OF LWIR DETECTORS. THE DETECTOR ELEMENTS OF THE ARRAY ARE FORMED BY AN ULTRA-THIN FILM OF A BOLOMETER MATERIAL POSSESSING THE HIGHEST TEMPERATURE COEFFICIENT OF RESISTANCE KNOWN, AND THE READOUT ELECTRONIC MICROCIRCUIT IS FABRICATED ON THE SAME SILICON CHIP NEXT TO THE ELEMENTS. THE RESULTANT DETECTOR ARRAYS POSSES FEATURES OF LOW COST, LOW WEIGHT, HIGH RESPONSIVITY, AND HIGH SENSITIVITY. THE LOW COST IS DUE TO A SINGLE BATCH PROCESS IN THE ARRAY FABRICATION. THE LOW WEIGHT IS DUE TO A MONOLITHIC ARRAY STRUCTURE REQUIRING NO COOLING. THE HIGH RESPONSIVITY IS DUE TO A LARGE TEMPERATURE COEFFICIENT OF RESISTIVITY (>15 PERCENT COMPARED TO 0.2 PERCENT FOR A CONVENTIONAL BOLOMETER) OF THE NEW BOLOMETER MATERIAL. THE HIGH SENSITIVITY IS DUE TO THE COMBINED EFFECTS OF HIGH RESPONSIVITY, LOW NOISE, AND HIGH THERMAL ISOLATION OF THE BOLOMETER FROM ITS SURROUNDINGS.