ALUMINUM GALLIUM NITRIDE HETEROSTRUCTURES FOR HIGH TEMPERATURE TRANSISTOR AND SENSOR APPLICATIONS

THE PROPOSED PROGRAM IS AIMED AT DEVELOPING ALX GA1-XN/GAN HETEROSTRUCTURE DEVICES FOR HIGH TEMPERATURE SENSOR AND ELECTRONICS APPLICATIONS. WE WILL FOCUSS ON AN ALXGA1-XN BASED HIGH ELECTRON MOBILITY TRANSISTOR (OR HEMT) FOR USE ASA HIGH TEMPERATURE MICROWAVE DEVICE OR AS A SENSITIVE ULTRAVIOLET DETECTOR. GAN HAS A LARGE BANDGAP OF 3.2 EV WHICH GIVES IT A GREATER BREAKDOWN VOLTAGE AND A HIGHER SATURATED ELECTRON VELOCITY THAN GAAS. GAN, IN ADDITION, ISSTABLE IN AIR TO AROUND 800 DEGREES CENTIGRADE WHICH MAKES IT IDEAL FOR HIGH TEMPERATURE HEMT DEVICE USE. HEMT DEVICES ARE EXCELLENT FOR BOTH POWER AND LOW NOISE AMPLIFICATION SINCE THEY POSSES A HIGH CARRIER CONCENTRATIONAND ENHANCED CARRIER MOBILITY. THEIR POWER AND NOISE PERFORMANCE INCREASES WITH THE POTENTIAL BARRIER AT THE HETEROSTRUCTURE INTERFACE. FOR FABRICATING ALXGA1-XN/GAN HEMTS IT IS THEREFORE HIGHLY DESIRED TO HAVE HIGH N-DOPED (LOW RESISTIVITY) ALXGA1-XN FILMS WITH THE HIGHEST POSSIBLE X-VALUE. TO DATE THIS HAS NOT RESULTED FROM ANY OF THE CONVENTIONAL (MOCVD, MBE, VPE, SPUTTERING) MATERIAL DEPOSITION TECHNIQUES. INFACT AIN HAS LONG BEEN KNOWN TO BEONE OF THE BEST INSULATORS AROUND. WE THEREFORE PROPOSE A PHASE I PROGRAM TO PRODUCE HIGH N-DOPED GOOD OPTICAL QUALITY ALXGA1-XN FILMS (FOR ALLOY COMPOSITIONS IN EXCESS OF 0.5) USING A UNIQUE ATOMIC LAYER EPITAXY APPROACH. ALL THE PRESENT DAY GROWTH AND DOPING PROCEDURES CANNOT PRODUCE LOW RESITIVITY ALXGA1-XN EPILAYERS(FOR X0.5). A SUCCESSFUL PHASE I PROGRAM COMBINED WITH OUR DEMONSTRATION OF HIGH QUALITY GAN FILMS AND ENHANCED ELECTRON MOBILITIES IN ALGAN/GAN HETEROJUNCTIONS WITH AL-CONCENTRATIONS LESS THAN 20% WILL FORM A STRONG BASIS FORA PHASE II HEMT FABRICATION EFFORT.