AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Tuesday Sessions
       Session NS-TuP

Paper NS-TuP31
ZnXCd1-XSe Ternary Semiconductor Nanoalloys

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Nanometer Scale Science and Technology Poster Session
Presenter: H. Lee, University of Florida
Authors: H. Lee, University of Florida
L. Hardison, University of Florida
H. Yang, University of Florida
V.D. Kleiman, University of Florida
P.H. Holloway, University of Florida
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ZnxCd1-xSe quantum dots have been synthesized by a high temperature colloidal method using a trioctylphosphine oxide (TOPO) solution. Oleic acid complexes of Cd and Zn were used for the metal sources in reactions that produced ZnxCd1-xSe nanoalloys. Nanoalloying was achieved during the one-step synthesis process that led to a ZnSe shell on the CdSe core. Reaction temperatures below 250oC led to less alloying and less spectral shifts as compared to dots synthesized at 320oC. Smaller nanocrystals were obtained at lower growth temperature due to a smaller critical radius of nucleation, leading to a large nucleation rate. ZnCdSe nanorods were also synthesized from CdSe/ZnSe coreshell nanorods via a solution thermal alloying process at 270~280oC. CdSe nanorods were prepared using tetradecylphosphonic acid (TDPA)/TOPO surfactants, and a ZnSe shell was grown on CdSe nanorods at 180~190oC. These nanorods were characterized as a function of alloying time using X-ray diffraction, Raman, transmission electron microscopy, and time-resolved photoluminescence spectroscopy. Femto-second transient absorption in the visible emission spectra was used to study the alloying mechanism(s). The decay of luminescence in ZnxCd1-xSe nanoalloys is best fit by stretched-exponential function and the significance of this observation will be discussed.