ULTRASTRUCTURED MATERIALS

THE MOST PROMISING CANDIDATE FOR THE NEXT GENERATION, HIGH SPEED ELECTRONIC DEVICES IS THE PSEUDOMORPHIC HIGH ELECTRON MOBILITY TRANSISTOR (PHEMT). DEVICES BASED ON PHEMT TECHNOLOGY HAVE DEMONSTRATED EXTREMELY HIGH CUT-OFF FREQUENCIES. FULL UTILIZATION OF THE MODULATION DOPING PHENOMENA CAN BE ACHIEVED BY INCREASING THE CONDUCTION BAND DISCONTINUITY BETWEEN THE INGAAS CHANNEL AND ALGAAS DONOR LAYER BY INCREASING THE INDIUM MOLE FRACTION TO 40%. IN ORDER TO PREVENT LATTICE STRAIN RELAXATION DUE TO THE LARGE LATTICE MISMATCH BETWEEN MATERIALS, CONVENTIONAL MBE MUST BE SUPPLEMENTED WITH THE ADVANCED GROWTH TECHNIQUES OF MIGRATION ENHANCED EPITAXY (MEE) AND PHASED LOCKED EPITAXY (PLE). PHASE I WILL DEVELOP THE MEE AND PLE TECHNIQUES REQUIRED TO GROW PHEMTS HAVING INGAAS CHANNELS WITH INDIUM MOLE FRACTIONS OF 40%. PHASE II WORK WILL EXTEND AND REFINE THE TECHNIQUES FOR THE MANUFACTURE OF A WIDER RANGE OF STRATEGIC ELECTRONIC MATERIALS.