Ultraviolet-Photoluminescence and Raman Properties of Mg$_{x}$Zn$_{1-x}$O Nanopowders$^{\ast }$

ORAL

Abstract

The Mg$_{x}$Zn$_{1-x}$O alloy system may provide a new UV optically tunable family of wide bandgap materials. ZnO has the hexagonal wurtzite structure of bandgap $\sim $ 3.3 eV while MgO has the NaCl cubic structure of bandgap $\sim $ 7.5 eV. Bandgap engineered alloys at the range $\sim $ 3.3 -- 7.0 were achieved. In this communication we present studies on the UV photoluminescence (PL) and Raman properties of wurtzite Mg$_{x}$Zn$_{1-x}$O nanopowders of average size $\sim $ 30 nm that were synthesized via the thermal decomposition method. For the studied composition range of $0\le x\le 0.26$, the room temperature UV-PL was found to be tuned by $\sim $ 0.25 eV towards the UV-spectral range, and the PL emission was established to be due to an excitonic-type recombination mechanism. The first-order LO Raman mode was found to exhibit a blueshift of $\sim$~33 cm$^{-1}$ and the second-order LO a shift of $\sim$~60 cm$^{-1}$. The LO-mode of the nanopowders is discussed in terms of a mixed A$_{1}$-E$_{1}$ symmetry phonon known as a quasi-LO mode. \newline $^{\ast }$L. Bergman, et. al, Appl. Phys. Lett. \textbf{88}, 023103 (2006)

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Authors

  • John Morrison

  • Xiang-Bai Chen

  • Jesse Huso

  • Heather Hoeck

  • James C. Evans

    The Evergreen State College, Department of Physics, University of Washington, University of Missouri-St. Louis, Portland State University, Whitman College, University of British Columbia, University of Portland, Dordt College, Calvin College, Evergreen State College, Department of Materials Science, Tmfy-MSE, The Royal Institute of Technology, Stockholm, Sweden, National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA, Department of Chemical Engineering and Materials Science, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA, Department of Physics, Portland State University, P.O. Box 751, Portland, OR 97207-0751, USA, Army Research Lab, Physics Dept., Washington State University, Chair of the Local Organizing Committee, Department of Physics, University of Puget Sound

  • Leah Bergman

    Physics Dept., University of Idaho, University of Idaho

  • James C. Evans

    The Evergreen State College, Department of Physics, University of Washington, University of Missouri-St. Louis, Portland State University, Whitman College, University of British Columbia, University of Portland, Dordt College, Calvin College, Evergreen State College, Department of Materials Science, Tmfy-MSE, The Royal Institute of Technology, Stockholm, Sweden, National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA, Department of Chemical Engineering and Materials Science, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA, Department of Physics, Portland State University, P.O. Box 751, Portland, OR 97207-0751, USA, Army Research Lab, Physics Dept., Washington State University, Chair of the Local Organizing Committee, Department of Physics, University of Puget Sound