Improved UV photosensing properties of high crystalline nickel oxide thin films: Role of yttrium doping

Abstract In this research article, we present the fabrication of a high-quality NiO thin film based UV photosensor as a function of different Yttrium(Y) content (0, 1, 2, and 3 wt%) which was carried out on soda-lime glass substrates via an eco-friendly nebulizer assisted spray pyrolysis method. The effect of various Y content on its growth and hence microstructure, surface morphology, elemental composition, photoluminescence, optical, and the current-voltage (I–V) characteristics of these deposited films were systematically analyzed in detail. The analysis of the X-ray diffraction patterns ensures a cubic phase in all the films with preferential orientation along the (111) plane. Room temperature Laser-Raman spectra under 532 nm excitation displayed 1LO and 2LO Raman modes for all the films. Field Emission Scanning Electron Microscope (FESEM) analysis of all the films reveals nanograins formation with dot-like particles. Moreover, the dopant introduction into NiO enhanced the absorption in the UV region and decreased the bandgap values from 3.61 to 3.42 eV. The recorded PL spectra exhibited six emission peaks at 390, 412, 438, 452, 475, and 524 nm for all the films. The obtained Y-doped NiO films exhibited outstanding UV photoresponse and photoelectric characteristics at 5 V bias voltage. The highest responsivity (20 ×10−2 A/W), detectivity (5.53 × 109 Jones), External Quantum efficiency (70%), and fast photoswitching speed was observed for 2% Y-doped NiO thin films. Further, we confirmed that the UV photosensing properties were strongly dependent on the selection of dopants with appropriate concentrations.