Electrodeposition and characterization of CdTe thin films on Mo foils using a two voltage technique

Polycrystalline thin film CdTe-based solar cells are one of the most promis ing candidates for low-cost terrestrial conversion of solar energy because of the optimum energy band gap (E-g = 1.44 eV) and high absorption coeffici ent of CdTe. In this work, a two-step electrodeposition technique has been used to prepare CdTe thin films from acidic solutions. In the first step, a thin Te rich CdTe layer was deposited at -300 mV (SCE) on a Mo foil substr ate. On top of this film, a Cd rich CdTe layer was deposited at more negati ve voltages. The resulting films showed good adherence to the substrate and very low contact resistance between the substrate and the p + Te rich CdTe layer. The composite film was of nearly stoichiometric composition. From X -ray diffraction results, the as-deposited films show very small grain size s but after annealing the grain size increases considerably showing very we ll-defined peaks. The morphological, structural and composition results of CdTe thin films obtained by Scanning Electron microscopy, X-ray diffraction , and X-ray fluorescence will be presented. Electrical properties such as c onductivity type and contact resistance values for the Mo/CdTe structures w ill also be presented. (C) 2000 Published by Elsevier Science B.V. All righ ts reserved.