Rafea, M Abdel and Roushdy, N (2009) Determination of the optical band gap for amorphous and nanocrystalline copper oxide thin films prepared by SILAR technique. Journal of Physics D: Applied Physics, 42 (1). 015413.
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Official URL: http://stacks.iop.org/0022-3727/42/i=1/a=015413
Amorphous copper oxide films were deposited using the SILAR technique. Both Cu 2 O and CuO crystallographic phases exist in deposited and annealed films. Crystallization and growth processes by annealing at temperatures up to 823 K form grains with nano- and micro-spherical shapes. The calculated crystallite size from the XRD measurement was found to be in the range 14â21 nm while nano-spheres in the diameter range 50â100 nm were observed by SEM micrographs. The band gap for amorphous film was found to be 2.3 eV which increased slowly to 2.4 eV by annealing the film at 373 K. This was explained by defect redistribution in amorphous films. Annealing in the temperature range 373â673 K decreased the band gap gradually to 1.85 eV. The decrease of the band gap with annealing temperature in the range 373â673 K agrees well with the Brus model of the energy gap confinement effect in nanostructured semiconducting materials. Annealing in the temperature range 673â823 K decreases the band gap slowly to 1.7 eV due to the smaller contribution of the confinement effect. Below 573 K, Cu 2 O is the most probable crystalline phase in the film, while Cu 2 O and CuO crystalline phases may coexist at annealing temperatures above 573 K due to further oxidation of Cu 2 O. A wider transmittance spectral window in the visible region was obtained by controlling the annealing conditions of the amorphous copper oxide film and its applicability to the window layer of solar cell was suggested.
|Deposited By:||Prof. Alexey Ivanov|
|Deposited On:||02 Nov 2011 00:15|
|Last Modified:||02 Nov 2011 00:47|
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