TWO-COLOR BIAS SELECTABLE PHOTODIODES FOR THERMOGRAPHY

WE WILL FABRICATE HGCDTE, FRONT-SIDE ILLUMINATED, ELECTRICALLY SELECTABLE, TWO-COLOR INFRARED DETECTOR ARRAYS FOR HIGH RESOLUTION BIOMEDICAL THERMOGRAPHY. TEMPERATURE RESOLUTIONS OF 0.01 DEGREES CENTIGRADE SHOULD BE ACHIEVABLE WITH THESE DEVICES. THE DEVICE IS A TWO TERMINAL, N-P-N HETEROSTRUCTURE WHICH CAN BE THOUGHT OF AS TWO BACK-TO-BACK DIODES. THROUGH PROPER SELECTION OF THE MATERIAL COMPOSITION AND APPLICATION OF AN APPROPRIATE BIAS, THE DEVICE CAN BE MADE SENSITIVE TO TWO DIFFERENT SPECTRAL BANDS AND WOULD BE USEFUL IN BIOMEDICAL THERMAL IMAGING APPLICATIONS WHERE TEMPERATURE DISCRIMINATION IS IMPORTANT. WITH GOOD JUNCTION CHARACTERISTICS, BACKGROUND-LIMITED PERFORMANCE (BLIP) SHOULD BE ACHIEVABLE IN BOTH BANDS. IN ADDITION, THE DEVICE REQUIRES ONLY TWO TERMINALS, THUS PERMITTING A MOSAIC OF DETECTORS TO BE HYBRIDIZED WITH A SILICON SIGNAL PROCESSOR USING EXISTING BUMP HYBRIDIZATION TECHNOLOGY. IN PHASE I, SPIRE WILL DESIGN, FABRICATE AND TEST THE TWO-COLOR HGCDTEIR DETECTORS IN A 4X4 CONFIGURATION. MOCVD MATERIALS TECHNOLOGY WILL BE USED AND A GATE WILL BE EMPLOYED TO CONTROL SURFACE LEAKAGE. THE DEVICES WILL BE CHARACTERIZED FOR SPECTRAL DETECTIVITY, RESPONSIVITY, SPECTRAL RESPONSE, AND NOISE PERFORMANCE. PHASE II WILL OPTIMIZE THE DEVICE DESIGN AND THE MOCVD DEPOSITION PARAMETERS FOR OPTIMAL SPECTRAL DETECTIVITY AND MAXIMUM EFFICIENCY.