ISOELECTRONIC DOPING TECHNIQUES

MONOLITHIC MICROWAVE INTEGRATED CIRCUITS (MMIC'S) MADE OF GAAS ARE BECOMING INCREASINGLY IMPORTANT FOR USE IN MILITARY SYSTEMS. A MAJOR LIMITATION TO ADVANCEMENT IN THIS FIELD IS THE QUALITY OF THE SEMI-INSULATINGGAAS SUBSTRATES AVAILABLE. SPIRE PROPOSES TO DEVELOP A TECHNIQUE FOR PRODUCING HIGH-QUALITY, LOW-DISLOCATION-DENSITY WAFERS BY THE USE OF AN ISOELECTRONICALLY DOPED GAAS BUFFER LAYER WHICH IS KNOWN TO REDUCE DEFECT PROPAGATION. THE ISOELECTRONIC DOPING OF THIS THIN LAYER IS EXPECTED TO AVOID THE PROBLEMS ENCOUNTERED WITH ISOELECTRONICALLY DOPED BULK SUBSTRATE MATERIALS AND SHOULD PERMIT THE DEPOSITION OF ADDITIONAL EPITAXIAL LAYERS OF DEVICE QUALITY. THE PHASE I EFFORT WILL SEEK TO DEMONSTRATE THE FEASIBILITY OF GROWING IN-DOPED GAAS BUFFER LAYERS IN A PRODUCTION-SIZE METALORGANIC CHEMICAL VAPOR DEPOSITION (MO-CVD) REACTOR AND TO ASSESS THEIR EFFECTIVENESS FOR DISLOCATION REDUCTION.