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Abstract
The present communication reports the preparation and physical characterization of CdTe thin films for photovoltaic application. The thin films of thickness 660 nm and 825 nm were deposited on glass and ITO coated glass substrates employing thermal vacuum evaporation deposition method. These as-deposited films were characterized using XRD, UV-Vis spectrophotometer, source meter, SEM and AFM for physical properties. The XRD patterns reveal that the films are crystallized zinc-blende structure of cubic phase with preferred orientation (111) as well as polycrystalline in nature. The optical and crystallographic parameters are calculated and widely discussed. The optical band gap is found in the range 1.52 - 1.94 eV and observed to decrease with thickness. The current-voltage characteristics show that the current is found to be decreased with thickness and the resistivity is increased. The SEM studies show that the films are homogeneous, uniform and free from crystal defects. The grains in the thin films are similar in size and densely packed. The AFM studies reveal that the surface roughness is observed to increase for higher thickness. The experimental results reveal that the films of thickness 825 nm may be used as absorber layer in CdTe/CdS thin film solar cells due to its optical band gap 1.52 eV which is almost identical with the optimum band gap of CdTe and good crystallinity.
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