STRAINED TYPE II SUPERLATTICE FOR LONG WAVELENGTH INFRARED DETECTORS

AS AN ALTERNATIVE TO MERCURY-CADMIUM TELLURIDE (MCT), WE PROPOSE TO INVESTIGATE THE OPTICAL PROPERTIES OF A RECENTLY INVENTED CLASS OF TYPE II STRAINED-LAYER SUPERLATTICES MADE OF (GA, AS)RELATED COMPOUNDS. THE NEW CONCEPT HAS ADVANTAGES COMPARED WITH PREVIOUS EFFORTS IN THAT SMALL BAND-GAPS MAY BE ACHIEVED WITH SUFFICIENTLYTHIN REPEATING LAYERS IN THE SUPERLATTICES SO THAT THEY HAVE GOOD OPTICAL ABSORPTION PROPERTIES AND FAVORABLE ELECTRICAL TRANSPORT PROPERTIES ORIGINAL CALCULATIONS HAVE INDICATED GA1-XINXSB/INAS TO BE THE BESTCHOICE FOR SUCH APPLICATION. VERY RECENTLY IT HAS BEEN SHOWN TO HAVETHE HIGHEST ABSORPTION COEFFICIENT AT 10UM WAVELENGTH COMPARED TO ALLOTHER SUPERLATTICE MATERIALS. TO EXPLORE THE POTENTIAL OF THIS MATERIAL SYSTEM, WE PROPOSE TO FABRICATE THEM BY MOLECULAR BEAM EPITAXY (MBE). THE MBE SYSTEM IS EQUIPPED WITH ADJUSTABLE COLUMN V CRACKER SOURCES AND THE GROWTH PROCESS IS AUTOMATED. THE SAMPLES WILL BE CHARACTERIZED OPTICALLY AND EVALUATED FOR INFRARED DETECTION APPLICATIONS IN THE 8-12 UM REGION. ANTICIPATED BENEFITS/POTENTICIAL COMMERCIAL APPLICATIONS OF THE RESEARCH OR DEVELOPMENT. A VERY FAVORABLE OPTICAL PROPERTIES OF THE STRAINED-LAYER TYPE II SUPERLATTICES SUGGEST THAT THEY COULD BE VERY USEFUL FOR INFRARED DETECTORS AND DETECTOR ARRAYS USED IN SPACE ASTRONOMY, PHYSICS AND ATMOSPHERIC STUDIES, AS WELL AS MEDICAL AND INDUSTRIAL THERMAL IMAGING APPLICATIONS.