Investigation of the growth conditions on the nano-structure and electrical properties of ZnS chiral sculptured thin films

The dependence of electrical properties of sculptured ZnS thin films on the number of pitches and the morphology/structure or type of the substrate is investigated by deposition of chiral sculpture ZnS thin films with different number of pitches on different substrates. Crystallographic structure of samples was obtained using X-ray diffraction (XRD) method. Surface physical morphology of samples was studied by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). Results showed that void fraction, grain size and the crystal structure of the produced films are strongly dependent on the initial nucleation and the number of pitches in the chiral structure. Both AFM and FESEM images clearly showed the cluster form growth of these structures. The electrical resistance measurements of the produced samples showed that the resistance is strongly dependent on the type of the substrate and the initial nucleation, while the structures grown on larger initial nuclei consist of larger void fraction and hence higher resistance. Investigation on the influence of film thickness (number of pitches) on the conductivity of films showed that sculptured thin films have a different behavior/characteristic to the ordinary thin films. The electrical resistance of the said samples was also investigated under UV radiation and it was observed that the film with highest porosity have highest resistance. (C) 2015 Elsevier B.V. All rights reserved.