X-RAY CADMIUM-ZINC-TELLURIDE FOCAL PLANE ARRAYS FOR MEDICAL IMAGING

A NEW CADMIUM-ZINC-TELLURIDE (CD(ZN)TE) LINEAR X-RAY FOCAL PLANE ARRAY FOR SCANNING AND STARING MEDICAL IMAGING APPLICATIONS IS BEING STUDIED. THE DESIGN IS BASED ON CD(ZN)TE PHOTODIODES, FABRICATED USING METALORGANIC CHEMICAL VAPOR DEPOSITION (MOCVD) AND ADVANCED ARRAY PROCESSING TECHNOLOGY. THESE FOCAL PLANE ARRAYS OFFER ADVANTAGES OF HIGHER SPATIAL AND ENERGY RESOLUTION AND BETTER SENSITIVITY THAN CONVENTIONAL FILM-PHOSPHOR AND SCINTILLATOR-PHOTODIODE/ PHOTOMULTIPLIER X-RAY DETECTORS. IN ADDITION, DUE TO INCREASED SENSITIVITY OF THESE DETECTOR ARRAYS, THE REQUIRED X-RAY DOSAGE TO PATIENTS CAN BE REDUCED. PHASE I WILL DEVELOP A SMALL ARRAY OF CD(ZN)TE PHOTODIODES. MOCVD WILL GROW A CD(ZN)TE EPITAXIAL LAYER ON ONE SIDE AND A MERCURY TELLURIDE (HGTE) LAYER ON THE OTHER SIDE OF HIGH RESISTIVITY CD(ZN)TE. TITANIUM/ALUMINUM LAYERS WILL FORM A SCHOTTKY JUNCTION ON THE CDTE LAYER AND HGTE WILL FORM AN OHMIC CONTACT ON THE BULK CD(ZN)TE. ARRAYS WITH 100 MU X 100 MU PIXEL SIZE WILL BE FABRICATED AND TESTED FOR PIXEL-TO-PIXEL UNIFORMITY. DURING PHASE II, LARGE ARRAYS WITH SMALLER PIXEL SIZE WILL BE DEVELOPED. IN ADDITION, A P-I-N DEVICE STRUCTURE WILL BE USED TO IMPROVE THE PERFORMANCE OF THESE DETECTOR ARRAYS AND COMMERCIALIZATION OF THE TECHNOLOGY WILL BE PURSUED.