Fabrication of Eu doped CdO [Al/Eu-nCdO/p-Si/Al] photodiodes by perfume atomizer based spray technique for opto-electronic applications

In this study, thin films of cadmium oxide (CdO) with different concentrations (0, 1, 3, and 5 wt%) of Eu doping were deposited onto Si and glass substrates by a novel and facile spray technique using simple perfume atomizer for the first time. Prepared films were characterized for structural, morphological, optical properties and the photo diode studies, using X-ray diffraction, scanning electron microscope, UV–Vis spectrophotometer, I–V characteristics, and fundamental parameters are reported. All the prepared Eu:CdO films exhibit cubic structure. The preferential orientation is along (200) plane. Scanning electron microscopy study indicates the growth of smooth and pin-hole free films with clusters of homogeneous grains. The values of band gap energy are found to be varying from 2.42 to 2.33 eV for various Eu doping concentration from 0 to 5 wt%. EDAX studies revealed the presence of Eu, Cd and O elements without any other impurities. FTIR spectra showed a peak at 575 cm⁻¹ confirming the stretching mode of Cd–O. The resistivity (ρ), high carrier concentration (n) and carrier mobility (μ) for 3 wt% CdO thin film are found to be 0.452 × 10⁻³(Ω.cm), 17.82 × 10²⁰ cm⁻³ and 7.757 cm²/V, respectively. Current-voltage measurements on the fabricated nanostructured Al/Eu-nCdO/p-Si/Al heterojunction device showed a non-linear electric characteristics indicating diode like behaviour.