Long Wave IR HgZnTe

IR DETECTOR MATERIAL, MERCURY CADMIUM TELLURIDE HAS BEEN THE MOST MATURES AND OFTEN A MATERIAL OF CHOICE FOR ADVACNED INFRARED DETECTION. HOWEVER, IT IS EXTREMELY DIFFICULT TO PRODUCE THE MATERIAL FOR DETECTION AT A WAVELENGTH GREATER THAN 14um. THIS PROBLEM IS DUE TO EXCCESSIVE FUNNELLING AND SURFACE LEAKAGE RELATED TO DARK CURRENTS. IN RECENT YEARS MERCURY ZINC TELLURIDE (MZT) HAS EMERGED AS A SUPERIOR ALTERNATIVE MATERIAL TO MCT WITH RESPECT TO MECHANICAL, CHEMICAL AND THERMAL STABILITY. THIS PROPOSAL DEALS WITH A NOVEL APPROACH TO PREPARE MZT CRYSTALS IN WHICH A) TUNNELING DARK CURRENTS ARE SUPPRESSED SIGNIFICANTLY, AND B) THE MINORITY CARRIER LIFE TIME ARE MAXIMIZED TO ACHIEVE NEAR THEORETICAL AUGER LIMITS. THE PROPOSED MATERIAL WILL HAVE N-TYPE CARRIER CONCENTRATION WELL BELOW 10 (14) CM (-3) AND WILL HAVE GREATLY REDUCED CONCENTRATION OF SHOCKLEY-READ RECOMBINATION CENTERS. THE PROPOSED APPROACH ENTAILS ENNEALING DONOR DOPED MZT SAMPLES UNDER PHSICO-CHEMICAL CONDITIONS SUCH THAT A KNOWN CONCENTRATION OF COMPENSATING Hg VACANCY ACCEPTORS IS INTRODUCED INTO THE SAMPLES. THIS COMPENSATION PROCESS WILL REDUCE N-TYPE CONCENTRATION TO WELL BELOW 10 (14) CM (-3). THE CONDITIONS OF ANNEAL WILL BE OPTIMIZED IN ORDER TO REDUCE THE CONCENTRATION OF FRENKEL DEFECTS WHICH ARE RESPONSIBLE FOR LIMITING CARRIER LIFE TIMES. PHASE I WORK WILL FOCUS ON PRODUCING MZT WAFERS WITH LOW N-TYPE CARRIER CONCENTRATION (<10 (14) CM (-3)) AND CARRIER LIFE TIMES APPROACHING THE AUGER LIMIT. PHASE II WORK WILL BE AIMED AT 1) OPTIMIZING THE PROCESS AND MATERIAL DEVELOPED IN PHASE 1 AND, 2) BUILDING LINEAR AND FOCAL PLANE ARRAYS USING THIS MATERIAL.