QUANTUM CONFINEMENT EFFECTS IN HETEROEPITAXIAL SILICON/ZINC SULFIDE (SI/ZNS) NANOSTRUCTURES PRODUCED BY METALLO-ORGANIC CHEMICAL VAPOR DEPOSITION

SILICON MULTIQUANTUM WELLS WITH LATTICE MATCHED ZNS BARRIERS WILL BE GROWN ON SILICON SUBSTRATES BY ORGANOMETALLIC CHEMICAL VAPOR DEPOSITION. SUCH SILICON NANOSTRUCTURES ARE EXPECTED TO EXHIBIT THE SAME QUANTUM CONFINEMENT EFFECTS THAT HAVE ALREADY BEEN REPORTED FOR POROUS SILICON, BUT NOW WITH A CAREFULLY CONTROLLED, PLANAR CRYSTAL STRUCTURE. ALTHOUGH SILICON QUANTUM WIRES PRODUCED BY ELECTROCHEMICAL ETCHING SHOW VISIBLE PHOTOLUMINESCENCE AND ELECTROLUMINESCENCE, THE FRACTAL NATURE OF THOSE STRUCTURES MAKES THE PREPARATION OF REPRODUCIBLE DEVICES UNLIKELY. BECAUSE THE SI/ZNS SUPERLATTICES WILL BE CONFIGURED AS WAVEGUIDES, ANALOGOUS TO ALGAAS/GAAS QUANTUM WELL STRUCTURES, IT IS ANTICIPATED THAT SILICON DIODE LASERS OPERATING AT VISIBLE WAVELENGTHS MAY BECOME POSSIBLE. VISIBLE PHOTOLUMINESCENCE HAS ALREADY BEEN REPORTED WITH SI/SI3N4 QUANTUM WELL STRUCTURES. BECAUSE ZNS CAN BE MADE CONDUCTING, THE CAPABILITY TO GENERATE ELECTROLUMINESCENCE UNDER RELATIVELY LOW ELECTRICAL BIAS IS EXPECTED. IN PHASE I, ZNS FILMS WILL BE PREPARED EPITAXIALLY BY MIXED OXIDE CHEMICAL VAPOR DEPOSITION (MOCVD) ON PERFECTLOY CLEANED SILICON SUBSTRATES, USING A PROCEDURE RECENTLY DEVELOPED AT THE UNVERSITY OF FLORIDA. SILICON FILMS WITH THICKNESS ON ORDER OF 50A WILL BE DEPOSITED, USING A PHOTO-ASSISTED DEPOSITION PROCESS AND SEVERAL SILICON-BASED PRECURSORS. THE GOAL OF PHASE I IS TO DEMONSTRATE PHOTOLUMINESCENCE FROM A SINGLE SILICON QUANTUM WELL. PHASE II WILL PROCEED TO INVESTIGATE MULTIQUANTUM WELLS, AND CONFIGURE THE DEVICES AS JUNCTION DIODES, TO SEARCH FOR VISIBLE ELECTROLUMINESCENCE.