Structural, optical and electrical properties of Ni doped ZnO nanostructures synthesized by solution combustion method

In this work, pure and Ni-doped ZnO nanostructures (NSs) with different concentrations of Ni (2, 4, 6%) were successfully prepared via solution combustion method. The TEM photograph shows the formation of flake-like structures with the decrease in size of NSs as the dopant concentration is increased. XRD investigation shows the hexagonal wurtzite structure of doped and undoped ZnO nanostructures with a NiO peak (200) as secondary phase for 4 and 6% dopant concentration level. Broadening of spectra of ZnO around 480 cm⁻¹ in FTIR spectra is observed with the increase of dopant concentration. UV–Visible spectra show the increase in absorbance when the dopant level (Ni²⁺) is increase from 2 to 4% in ZnO and decrease in absorbance with further increase in dopant level to 6%. An increase in energy band gap is observed in Ni (6%)-doped ZnO due to due to the sp–d interactions taking place between the band electrons and the localised d electrons of Ni²⁺ ions (Burstein-Moss effect). I–V characteristics reveal the increase in current with the increase in dopant level from 2 to 4% and decrease in current when the dopant level is further increased to 6% which is in agreement with the Burstein-Moss effect.