Solution Phase Synthesis of Semiconductor Nanowires
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Solution Phase Synthesis of Semiconductor Nanowires Katherine L. Hull1,2, James W. Grebinski2, Jing Zhang3, Thomas H. Kosel3, Masaru Kuno1,2* 1 Department of Chemistry and Biochemistry, 2Notre Dame Radiation Laboratory, and 3 Department of Electrical Engineering Notre Dame, IN 46556 ABSTRACT The solution phase synthesis of narrow diameter CdSe and PbSe nanowires (NWs) is described. Crystalline NWs with lengths between 1-10 µm are obtained using a seeded solution approach, whereby NW growth is catalyzed by Au/Bi core/shell nanoparticles (NPs). A gold biphasic reduction step results in 1.5 (3) nm diameter Au NPs and is followed by the thermolysis of trialkylbismuthines to yield low melting, bimetallic particles with diameters less than 3 nm. These Au/Bi NPs are catalytically active towards the growth of similar diameter CdSe NWs (~7 nm) that exhibit quantum confinement effects. By varying the ratio of Cd (or Pb) to Se, both straight and branched NWs can be obtained, with branched structures including v-shapes, tripods, and y-shapes in the case of CdSe and t-shapes in the case of PbSe. Structural characterization shows that both straight and branched CdSe NWs grow along either the zinc blende (ZB) or wurtzite (W) directions. Conversely, PbSe has a rocksalt crystal structure, and both straight and branched NWs grow along directions. INTRODUCTION Among the methods available for synthesizing narrow diameter semiconductor nanowires (NWs), a seeded solution approach, introduced in the mid 90’s, has been demonstrated as a viable means to making high quality material. [1] This technique offers significant advantages over the more traditional vapor-liquid-solid (VLS) approach [2], which requires high reaction temperatures (800-1000 °C). The solution phase approach can be conducted at temperatures less than 400 °C, and the product yields are potentially much higher. More importantly, the presence of surface binding surfactants reduces the potential for oxide formation and renders the material soluble, enabling future surface functionalization chemistries. In addition, the resulting solutionbased wires are some of the narrowest to date (
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