The effect of hydrogen on the conductivity of ZnO nanoparticles has implications for nanoscale optoelectronic devices. In this study, infrared reflectance spectra of as-grown and hydrogen-annealed ZnO nanoparticles were measured at near-normal incidence. The as-grown particles were electrically semi-insulating and show reflectance spectra characteristic of insulating ionic crystals. Samples annealed in hydrogen showed a significant increase in electrical conductivity and free-carrier absorption. A difference was observed in the reststrahlen line shape of the conductive sample compared to that of the as-grown sample. The effective medium approximation was applied to model the reflectance and absorption spectra. The agreement between experimental results and the model suggests that the nanoparticles have inhomogeneous carrier concentrations. Exposure to oxygen for several hours led to a significant decrease in carrier concentration, possibly due to the adsorption of negative oxygen molecules on the nanoparticle surfaces.
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15 August 2007
Research Article|
August 29 2007
Infrared and Raman spectroscopy of ZnO nanoparticles annealed in hydrogen
W. M. Hlaing Oo;
W. M. Hlaing Oo
Department of Physics and Astronomy,
Washington State University
, Pullman, Washington 99164-2814, USA
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M. D. McCluskey;
M. D. McCluskey
a)
Department of Physics and Astronomy,
Washington State University
, Pullman, Washington 99164-2814, USA
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J. Huso;
J. Huso
Department of Physics,
University of Idaho
, Moscow, Idaho 83844, USA
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L. Bergman
L. Bergman
Department of Physics,
University of Idaho
, Moscow, Idaho 83844, USA
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a)
Author to whom correspondence should be addressed; electronic mail: mattmcc@wsu.edu
J. Appl. Phys. 102, 043529 (2007)
Article history
Received:
April 18 2007
Accepted:
July 09 2007
Citation
W. M. Hlaing Oo, M. D. McCluskey, J. Huso, L. Bergman; Infrared and Raman spectroscopy of ZnO nanoparticles annealed in hydrogen. J. Appl. Phys. 15 August 2007; 102 (4): 043529. https://doi.org/10.1063/1.2773635
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