In the present study, the chemical spray pyrolysis method has been taken for synthesis of iron doped zinc oxide (ZnO:Fe) thin films. All the films have been deposited at a constant substrate temperature of 400ºC and the dopant (iron) concentration varied in the range, 0 -6 at. %. The X-ray diffraction (XRD) spectra of all as-grown films showed the existence of hexagonal wurtzite crystal structure without any other impurity phases. However, the predominant orientation changed from (002) to (101) plane with the increase of doping concentration. The surface morphology of as-prepared ZnO:Fe samples were viewed by scanning electron microscopy (SEM), which showed irregular shaped grains distributed over the substrate surface. The photoluminescence spectra exhibited UV-Visible and green emissions with suppressed intensity with the rise of Fe-content in the films.
…………………………………………………………………………………………………….... Introduction:-The application of zinc oxide (ZnO) thin films is not limited to use as (i) an antireflection coating in inorganic photovoltaic cell [1], but also as (ii) an electron transport material in dye sensitized and hybrid solar cells (DSC and HSC) [2], (iii) an optical spacer in polymer solar cell [3] (iv) planar displays because of good transparency, suitable refractive index and have potential to form textured deposition via anisotropic growth [4] and also (v) an interesting material for designing semiconductor devices [5]. Recently, ZnO is emerged as an alternating material to tin doped indium oxide (ITO) and tin oxide (SnO 2 ) thin films, which are used as transparent conducting oxide (TCO) layers in solar cell applications [6,7]. Because of its low cost, non-toxicity, huge availability, direct and wide band gap (3.37 eV) at room temperature, high optical transmittance mostly in Vis-NIR region makes it a potential material for optoelectronic device applications like laser diodes, light emitting diodes and photo sensors [8]. However, the investigations on properties of pure and doped ZnO films still attracts the attention of many researchers. The physical characteristics of ZnO films can be controlled by either adequate doping or annealing processes. Various dopants like aluminum (Al), indium (In), boron (B), copper (Cu), gallium (Ga), molybdenum (Mo), iron (Fe), magnesium (Mg), chromium (Cr), cobalt (Co) and nickel (Ni) have been used in the literature in order to deposit high conductivity ZnO films. Out of these, iron (Fe) (transition metal) doped ZnO has been recognized as a promising material [9][10][11]. In general, Fe-doped ZnO (FZO) films exhibit n-type electrical conductivity with hexagonal wurtzite crystal structure along with reduced band gap from 3.3 eV to 2.75 eV [12][13][14]
