SUPERLATTICE INFRARED PHOTO-TRANSISTORS USING INTERSUBBAND TRANSITION

TARGET DETECTION AND TRACKING IN THE WAVELENGTH RANGE OF 3 TO 12 UM WITH GREATLY INCREASED SENSITIVITY LEVELS AND SPATIAL RESOLUTION. THE PRINCIPLE OF THE APPROACH IS BASED UPON THE INTER-CONDUCTION SUBBAND (THEREAFTER REFERRED TO AS INTERSUBBAND) ABSORPTION FOLLOWED BY PHOTOEXCITED ELECTRONS TUNNELING OUT OF RESONANTLY ALIGNED ADJACENT QUANTUM WELLS. THIS PROCESS PRODUCES HOT ELECTRONS AND THUS THE PHOTOCURRENT IS EFFICIENTLY COLLECTED. THE DETECTIVITY OF THE ALXGA1-XAS/GAAS SUPERLATTICE DETECTORS IS ESTIMATED D*8.3UM=10E10/CM(HZ)1/2/W, COMPARABLE TO TYPICAL BACKGROUND-LIMITED HGCDTE PHOTOCONDUCTIVE DETECTORS. WE WILL ANALYZE THEORETICALLY THE DESIGN AND THE PERFORMANCE OF SUCH TRANSISTOR CONFIGURATIONS. THE APPROACH PROPOSED FOR FABRICATION OF THE SUPERLATTICE PHOTO-TRANSISTOR USES THE COMMERCIAL AVAILABLE MBE MATERIAL AND SIMPLE LASER INTERFERENCE PATTERNING. IF THE CONCEPT IS DEMONSTRATED, THE PRODUCTION CAN BE DONE READILY.