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Study On Synthesis And Photoluminescence Of Semiconductor ZnCdSe Nanowires And CuFeS2 Nanoparticles

Posted on:2011-11-23Degree:MasterType:Thesis
Country:ChinaCandidate:H Q MaFull Text:PDF
GTID:2121360308468562Subject:Condensed matter physics
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Nano-materials with novel physical and chemical properties different from bulk materials, become more important in the fields, such as renewable energy, environmental protection and so on. In this article, the synthesis of ternary CuFeS2 nanoparticles with chalcopyrite structure which viaed the solventothermal reaction route at 180-200℃, and the growth of ZnCdSe alloy nanowires with hexagonal structure which viaed gas phase method with Vapor-Liquid-Solid (VLS) mechanism are reported. The morphology and structure of two nanomaterials were characterized by scanning electron microscopy, high-resolution transmission electron microscope and X-ray diffraction. The as-prepared CuFeS2 nanoparticles and alloy ZnCdSe nanowires are all high phase-purity. The morphology of CuFeS2 nanoparticles were varied significantly according to reaction conditions. The diameter of ZnCdSe nanowires was also affected by variation of ratio of two reactants of ingredients. The optical properties of the CuFeS2 nanoparticles and ZnCdSe nanowires have been studied by UV-visible absorption spectroscopy, near-field scanning optical microscopy, fluorescence spectroscopy. The band gap of CuFeS2 nanoparticles has been detected to be 0.673 eV, slightly larger than previously reported (0.6 eV). The wider gap possibly resulted from the nano-size effect. The observed blue emission of CuFeS2 nanoparticles irradiated by the 325nm laser beam was originated from the inner shell transition of 3Eg→1A1g in the Cu+of CuFeS2 and coincided to the PL image. For alloy ZnCdSe nanowires, the each component in the compound was calculated by Vegard Law based on the PL spectrum. The tunable wavelength of the emission light between the 521nm-717nm is achived in this study. A strong defect luminescence was found as increase of Zn content in the alloy ZnCdSe nanowires, while the PL peak between 521nm-533nm did not change obviously. Increase of the Cd content did not result in the defect luminescence. The reasons for this phenomenon may due to the defect levels in ZnSe generally include Zn ions and Se ion vacancies, interstitial impurity ions or other defects,Se vacancy to form a double-donor level, while the Zn vacancy is an acceptor-type defects The new growth of ZnSe crystals, light-emitting layer is bound to Zn vacancies, emission peak is Zn vacancy conduction band electron and hole recombination by trapping. The ternary semiconductor nanowires with the tunable optical properties may have potential application in the nano-lasers technology.
Keywords/Search Tags:nano-materials, semiconductor, CuFeS2, ZnCdSe, nano-particles, nanowires, photoluminescence
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