Browsing by Author "Bai, S. N."

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Effect of alumina doping on structural, electrical, and optical properties of sputtered ZnO thin films
(2006-11-25)
Bai, S. N.
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Tseng, T. Y.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
A systematic study of the influence of alumina (Al2O3) doping on the optical, electrical, and structural characteristics of sputtered ZnO thin films is reported in this study. The ZnO thin films were prepared on 1737F Coming glass substrates by R.F. magnetron sputtering from a ZnO target mixed with Al2O3 of 0-4 wt.%. X-ray diffraction (XRD) analysis demonstrates that the ZnO thin films with Al2O3 of 0-4 wt.% have a highly (002) preferred orientation with only one intense diffraction peak with a full width at half maximum (FWEM) less than 0.5 degrees. The electrical properties of the Al2O3-doped ZnO thin films appear to be strongly dependent on the Al2O3 concentration. The resistivity of the films decreases from 74 Omega(.)cm to 2.2 x 10(-3) Omega(.)cm as the Al2O3 content increases from 0 to 4 wt.%. The optical transmittance of the Al2O3-doped ZnO thin films is studied as a function of wavelength in the range 200-800 nm. It exhibits high transparency in the visible-NIR wavelength region with some interference fringes and sharp ultraviolet absorption edges. The optical bandgap of the Al2O3-doped ZnO thin films show a short-wavelength shift with increasing of Al2O3 content. (c) 2006 Elsevier B.V. All rights reserved.
Structural and optical properties of Al-doped ZnO nanowires synthesized by hydrothermal method
(2007-12-03)
Bai, S. N.
;
Tsai, H. H.
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Tseng, T. Y.
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The growth of one dimensional Al-doped ZnO nanowires on a silicon substrate with a ZnO seeding layer by using a low temperature hydrothermal method is demonstrated. The structural and optical characteristics of the solution-grown Al-doped ZnO nanowires were studied using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and cathodoluminescence (CL) measurements. The FE-SEM images show that the ZnO nanowires are hexagonal column shaped and stand perpendicularly on the silicon substrate. It is found in XRD patterns that the ZnO nanowires annealed at various temperatures are all wurtzite crystal structure and have (002) preferred orientation. As the annealing temperature changed, the intensity of (100) and (10 1) peaks reveals distinct change. The CL spectra show the as-grown ZnO nanowires display a weak and narrow UVemission centered at 376 nm. A strong and very broad green-yellow emission band with a center at 575 nm as well as a shoulder like orange-red emission band centering at 625 nm is also demonstrated. It is shown that the luminescence intensity centered at 376 nm increased, the shoulder like emission centered at 625 nm decreased but emission centered at 575 nm disappeared after thermal annealing treatment in oxygen atmosphere. (C) 2007 Elsevier B.V. All rights reserved.