LOW DEFECT DENSITY GAAS ON PATTERNED SI

THE MONOLITHIC INTEGRATION OF GAAS BASED PHOTONIC DEVICES (E.G. LASERS) WITH THE SI BASED VLSI TECHNOLOGY HAS NOT YET OVERCOME THE HIGH DEFECT DENSITY IN THE GAAS (10E6-10E7 PER CM2). LASERS FABRICATED IN GAAS ON SI DIE IN MINUTES BECAUSE OF THE HIGH DENSITY OF DEFECTS AT THE GAAS/SI INTERFACE DUE TO THE LARGE MISMATCH BETWEEN THE TWO MATERIALS. NASSER KARAM'S PHASE I SBIR SAYS YOU CAN SOLVE THIS PROBLEM BY ARTIFICIALLY LIMITING THE NUMBER OF NUCLEATION SITES ON SAWTOOTH PATTERNED SI SUBSTRATES (0.2 MICROMETER PERIOD) AND PREVENTING THE FORMATION OF DISLOCATIONS VIA A THIN OXIDE LAYER (AMORPHOUS AND LESS THAN 5 NM) WHICH ACCOMMODATES THE GAAS/SI LATTICE MISMATCH. THE THIN OXIDE FILM ADHERES STRONGLY TO THE V-SHAPED PATTERNED SI AND TRANSMITS THE CRYSTAL SYMMETRY BUT NOT THE EXACT LOCATION OF THE ATOMS, HENCE ELIMINATING DISLOCATIONS (THE CAUSE OF THE PROBLEM). THE RESEARCH PROGRAM WILL DEMONSTRATE THE REDUCED DEFECT DENSITY IN GAAS (LESS THAN 10E5 PER CME2) AND A WORKING LASER. LARGE-AREA WAFER PATTERNING IS DONE BY HOLOGRAPHIC LITHOGRAPHY, AND FILMS ARE DEPOSITED BY LOW PRESSURE METALORGANIC CHEMICAL VAPOR DEPOSITION.