Thin layers of Fe-doped ZnO deposited by spin-coating for electrolysis and photodetector applications

The effect of iron concentration on the microstructural and structural properties of ZnO for electrolysis and photodetector applications was investigated. The thin layers of un-doped and doped ZnO with different percentages of Fe (2, 4, and 6 wt.%) were deposited by spin-coating on glass substrates. Sample characterization was done by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), UV−Vis absorption spectra and X-ray photoelectron spectroscopy (XPS). Structural measurements by XRD showed that all the layers were composed of polycrystallines with a hexagonal Wurtzite structure. Two new peaks were also discovered after the doping process belonging to the Fe₂O₄ (400) and (440) crystal phase. Morphological analysis showed that the surface roughness values of ZnO layers ranged between 8 and 45 nm. XPS studies confirmed the presence of Fe in 3+ states in ZnO layers. An average transmittance of 90% was measured by UV−Vis in the wavelength range of 200−900 nm. The values of the energy gap (E_g) decreased with an increase in the concentration of Fe. AFM topography results confirmed that ZnO-based thin layers had a relatively uniform surface. The efficiency of these samples has been confirmed for their use in many electrical applications, including photodetectors and electrolysis of contaminated solutions.