Highly efficient ultraviolet photodetector based on molybdenum-doped nanostructured NiO/ITO thin film

Nanostructured pure and molybdenum (Mo)-doped nickel oxide (NiO) thin films with various concentrations of Mo dopants were successfully sputtered on indium-doped tin oxide (ITO) substrates to apply in the ultraviolet (UV) photodetector sensors. The influence of Mo concentration on the thin films' structural, morphological, and optical properties was studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive X-ray, and UV-Vis spectrophotometer. The XRD studies confirm that all the prepared films are polycrystalline and possess a cubic phase structure. The FE-SEM images suggest that the distribution of the prepared samples on the substrate is homogeneous and free from any cracks. Spectrophotometry studies reveal the decrement of the optical band gap with the increase of Mo concentration in NiO thin films. All thin-film current-voltage curves measured under dark conditions and UV illumination of 390 nm showed Ohmic contacts. A noticeable improvement in the responsivity and external quantum efficiency (EQE) with the increased Mo concentration was detected. The metal-semiconductor-metal (MSM) employed in NiO thin films showed maximum responsivity and EQE of 539 mA/W and 171.4% at 390 nm, respectively, for the sample with 1.73 at% Mo doping.

Automated summary

The influence of molybdenum (Mo) doping concentration on the structural, morphological, and optical properties of nanostructured pure and Mo-doped nickel oxide (NiO) thin films was investigated. The results showed that increasing Mo concentration led to a decrease in the optical band gap of NiO thin films and improved responsivity and external quantum efficiency (EQE) under UV illumination.