Authors: Shafi Ullah Miguel Mollar Bernabé Marí
Publish Date: 2016/05/14
Volume: 20, Issue: 8, Pages: 2251-2257
Abstract
CuGaSe2 and CuGaS2 polycrystalline thin film absorbers were prepared by onestep electrodeposition from an aqueous electrolyte containing CuCl2 GaCl3 and H2SeO3 The pH of the solution was adjusted to 23 by adding HCl and KOH Annealing improved crystallinity of CuGaSe2 and further annealing in sulphur atmosphere was required to obtain CuGaS2 layers The morphology topography chemical composition and crystal structure of the deposited thin films were analysed by scanning electron microscopy atomic force microscopy energy dispersive spectroscopy and Xray diffraction respectively XRay diffraction showed that the asdeposited CuGaSe2 film exhibited poor crystallinity but which improved dramatically when the layers were annealed in forming gas atmosphere for 40 min Subsequent sulphurization of CuGaSe2 films was performed at 400 °C for 10 min in presence of molecular sulphur and under forming gas atmosphere The effect of sulphurization was the conversion of CuGaSe2 into CuGaS2 The formation of CuGaS2 thin films was evidenced by the shift observed in the Xray diffraction pattern and by the blue shift of the optical bandgap The bandgap of CuGaSe2 was found to be 166 eV while for CuGaS2 it raised up to 22 eV A broad intermediate absorption band associated to Cr and centred at 163 eV was observed in Crdoped CuGaS2 filmsThis work was supported by Ministerio de Economía y Competitividad ENE201346624C44R and Generalitat Valenciana Prometeus 2014/044 One of the authors S Ullah acknowledges the European Union IDEASCall3 Innovation and Design for EuroAsian scholars for its financial support
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