RADIATION-HARD GAAS BIPOLAR CIRCUITS FOR HIGH FREQUENCY APPLICATIONS

WE PROPOSE TO DEVELOP ULTRA RADIATION-HARD COMPLEMENTARY HETEROJUNCTION BIPOLAR TRANSISTOR (CHBT) CIRCUITS FOR HIGH FREQUENCY APPLICATIONS SUITABLE FOR DENSE SPACEBORNE SYSTEMS. WE WILL DEVELOP A SELF-ALIGNED BASE OHMIC METAL (SABM) PROCESS WITH THIN BASE STRUCTURES TO ACHIEVE VERY HIGH CUT-OFF FREQUENCIES CLOSE TO 80 GHZ. WE WILL OPTIMIZE THE PERFORMANCE OF N-P-N AND P-N-P DEVICES ON THE SAME CHIP USING GAALAS/GAAS HETEROSTRUCTURES FOR IMPROVING THE PACKAGING DENSITY. THE CHBT DEVICES WILL BE SPECIALLY DEVELOPED FOR HIGH SPEED ANALOG SYSTEMS SUCH AS A/D CONVERTERS FOR PRESENT-DAY AND FUTURE SPACE SYSTEMS. IN PHASE I WE WILL MODEL THE CHBT DEVICE, DELINEATE ITS FABRICATION PROCESS, DESIGN THE DEVICE STRUCTURE THUS ADDRESSING SOLUTIONS TO CRITICAL ISSUES INVOLVING RADIATION HARDNESS, PACKAGING DENSITY, POWER AND NOISE PERFORMANCE. WE WILL DESIGN A TEST CHIP TO DEMONSTRATE THE CHBT'S HIGH SPEED, LOW NOISE AND LOW POWER CAPABILITY. SINCE THESE DEVICES ARE BUILT ON THIN EPITAXIAL FILMS ON SEMI-INSULATING GAAS SUBSTRATE, THEY ARE ULTRA-RADIATION HARD MAKING THEM IDEALLY SUITABLE FOR USE IN RADIATION-RICH ENVIRONMENTS.