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Sn doped ZnO Thin Films Prepared by Pulsed Laser Deposition for Photovoltaic Applications |
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PP: 107-111 |
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Author(s) |
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I. Ali,
Z. Ullah,
K. Siraj,
M. S. Rafique,
M. Khaleeq-ur-Rahman,
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Abstract |
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| The objective of the present research work is to prepare various compositions of Sn doped ZnO thin films on a single crystal silicon (1 0 0) substrate via pulsed laser deposition technique, for investigation of valuable structural and optical properties. For this purpose, targets of pure and Sn-ZnO were prepared in the form of compressed, sintered and densified pellets by solid state reaction method. A KrF excimer laser (λ=248 nm, τ=20 ns, El = 20 mJ and Φl=1 J/cm2) was employed to deposit various thin films on silicon substrate. Post deposition annealing of all the Sn-ZnO thin films was carried out at 300 ˚C, and their structural and optical properties were investigated by X-ray diffraction (XRD) and Spectroscopic Ellipsometry (SE), respectively. It was observed from XRD results that ZnO (0 0 2) and SnO2 (2 1 0) were preferred planes orientations for all the Sn-ZnO thin films. The presence of SnO2 peak showed that SnO2 was epitaxialy included in ZnO matrix. The crystallite size of all the thin films was measured with the help of Scherrer‘s formula and it was decreased with the increase of Sn concentration in ZnO. Spectroscopic ellipsometry analysis showed that the values of refractive index (n) and extinction coefficient (k) were increased and optical band gap of the thin films was reduced with addition of Sn contents in ZnO thin films. The modification in band gap energy could be attributed to the crystallites size of the thin film; the decrease in crystallite size decreased the band gap energy, which makes the thin films valuable for variety of photovoltaic applications. |
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