Development of CdMnTe thin films using electroplating technique for opto-electronic device applications

Cathodic electrodeposition technique has been successfully used to achieve the growth of polycrystalline CdMnTe ternary compound thin films at different cathodic potentials. The choice of various cathodic potentials used in this work was made from the cyclic voltammogram results. The CdMnTe thin films were electroplated from electrolytes containing CdSO4, TeO2 and MnSO4 center dot H2O in an acidic aqueous medium. The electrodeposition was carried out on glass/fluorine-doped tin oxide {FTO} substrates. The structural, optical, morphological and electrical properties of the CdMnTe thin films were studied using X-ray diffraction (XRD), UV-Vis spectroscopy, scanning electron microscopy (SEM), current-voltage (I-V) characteristics and photo-electro-chemical (PEC) cell measurements respectively. The materials investigated in this work were explored under three different conditions namely: as-deposited (AD), heat-treated ordinarily in air (HT) and heat-treated in air in the presence of CdCl2 surface treatment (CC). Results from the XRD showed that the electrodeposited films are polycrystalline with the presence of CdTexOy and CdMnTe peaks. The electroplated films have cubic crystal structures and the preferred orientation was found to be along the (111) plane. The optical energy bandgaps of the thin films were found to be deposition potential dependent. Electrical conductivity types namely p- and n-type conductivity were also obtained at different cathodic potentials using photo-electro-chemical cell measurement technique for as-deposited and heat-treated materials.