GROWTH OF BULK II-VI CRYSTALS FOR VISIBLE LIGHT EMITTERS

HIGH QUALITY ZINC TELLURIDE (ZNTE) AND ZINC SELENIDE (ZNSE) SUBSTRATES ARE REQUIRED FOR THE CURRENT DEVELOPMENT OF BLUE AND GREEN LIGHT EMITTING DEVICES FABRICATED BY MOLECULAR BEAM EPITAXY (MBE) AND ORGANIC METALLIC VAPOR PHASE EPITAXY (OMVPE) PROCESSES. A SUITABLE BULK GROWTH TECHNIQUE WILL NOT ONLY HAVE THE POTENTIAL TO PRODUCE LARGE, HIGH PURITY, LOW DISLOCATION, HEAVILY DOPED SUBSTRATES, BUT WILL ALSO HAVE POTENTIAL TO EVOLVE INTO A LOW COST SUBSTRATE PRODUCTION PROCESS. THIS PROJECT WILL INVESTIGATE AND IMPROVE THE HIGH PRESSURE VERTICAL BRIDGMAN BULK GROWTH TECHNIQUE FOR SUBSTRATE PRODUCTION. AN UNDOPED ZNSE MONOCRYSTAL PREVIOUSLY GROWN WITH THIS TECHNIQUE WILL BE CHARACTERIZED AS A BENCHMARK. HEAVY DOPING WILL BE USED TO PROVIDE LATTICE STRENGTHENING RESULTING IN LOW DISLOCATION P-TYPE ZNTE AND N-TYPE ZNSE. CHEMICAL VAPOR DEPOSITED (CVD) ZNSE AND VERTICALLY SOLIDIFIED ZINC AND TELLURIUM WILL BE USED AS STARTING MATERIALS AFTER PURITY ANALYSIS. FINISHED CRYSTALS WILL BE CHARACTERIZED BY X-RAY TOPOGRAPHY FOR DEFECT STRUCTURE, AND BY HALL MEASUREMENTS FOR PURITY AND CONDUCTIVITY. PHASE II FEASIBILITY WILL BE INDICATED BY HIGH CONDUCTIVITY DOPED SINGLE CRYSTALS WITH REDUCED DISLOCATION DEFECTS WHEN COMPARED TO UNDOPED CRYSTALS. ANTICIPATED BENEFITS/POTENTIAL APPLICATIONS - HIGH QUALITY SUBSTRATES OF THESE MATERIALS WILL AID THE DEVELOPMENT OF BLUE AND GREEN LIGHT EMITTING DEVICES FABRICATED BY MBE AND OMVPE PROCESSES. THIS BULK GROWTH TECHNIQUE COULD EVOLVE INTO A COST EFFECTIVE SUBSTRATE PRODUCTION PROCESS.