Improved optical and electrical properties of Fe doped ZnO nanostructures facilely deposited by low-cost SILAR method for photosensor applications

The method of successive ionic layer adsorption and reaction (SILAR) was used to make Fe doped ZnO thin films by varying Fe concentrations (0, 2, 4, 6, and 8%). The prepared films were using the various analytical techniques such as X-ray diffraction (XRD), Field Emission scanning electron microscope (FESEM), Energy dispersive X-ray analysis (EDX), UV-Visible spectroscopy, photoluminescence (PL) spectroscopy and photosensing properties. XRD studies revealed the presence of Fe at the ZnO lattice, and all the prepared films exhibit hexagonal wurtzite structure. The SEM micrographs revealed the agglomerated particles over the surface of thin films. The UV–Vis studies showed that the optical band gap of undoped ZnO and 4% ZnO:Fe thin film were decreasing from 3.42 to 3.32 eV and started to increase up to 3.41 eV for further increase in Fe concentrations. The PL studies showed the emission centers at 393, 415, 435, 450, 480, and 525 nm. The 4% ZnO:Fe thin film has the maximum photoluminescence intensity due to the increasing Zn and O vacant sites, occupation of Fe2+ ions in the ZnO lattice revealed the enhancement of photosensing behavior. The photo detection properties and its significant parameters such as responsivity (R), External quantum efficiency (EQE) and detectivity (D*) of 4% ZnO:Fe thin film were determined and found to be as 1.96 × 10−1 AW−1, 45.83% and 4.95 × 1010 Jones respectively which is higher than other prepared sample films.