Study On The Enhanced Photoelectric Response Of Ni-Doped ZnO Nanorod Films

As a metal oxide semiconductor material,ZnO(zinc oxide)has a band gap of 3.37 eV and exciton binding energy of 60 meV,which is much higher than other wide band gap semiconductor materials.It has broad application prospects in the field of optoelectronic devices,and can be applied to luminescent materials,photocatalysts,solar cells and photodetectors.At present,researchers use different synthesis methods to prepare ZnO thin films,and doped different elements in ZnO thin films to achieve the regulation of the photoelectric properties of ZnO thin films.In this paper,ZnO nanorod array films were prepared by a simple hydrothermal synthesis method.The surface of ZnO nanorod array films was modified by using nickel acetate as Ni source.The Ni-doped ZnO nanorod array films were obtained by annealing.The structure of Ni-doped ZnO nanorod array films was characterized by means of SEM?XRD?PL and XPS.The photoelectric properties were tested by self-made photoelectric performance platform,and the mechanism of Ni-doping was discussed.In the first part,pure ZnO nanorod array films were synthesized by hydrothermal method.Then,in different nickel acetate concentration solutions,ZnO nanorod array films doped with different concentration of Ni were prepared by dipping and pulling method.The photoelectric properties were tested by self-made photoelectric performance platform.The results show that Ni doping does not affect the crystal structure of ZnO nanorod arrays,but changes the lattice constants,which results in(002)peak shift.Doping Ni enhances the photoresponsiveness of ZnO nanorod arrays.The maximum photoresponsiveness can reach 312.1,which is 38 times higher than that of pure ZnO nanorod arrays.The second part is to systematically explore the mechanism of enhancing the optical responsiveness of ZnO nanorod arrays with Ni doping by changing different process parameters,such as annealing temperature,Ni doping concentration and the wavelength of excitation light,on the basis of the first part.The effects of annealing temperature,Ni doping concentration and excitation light source of different wavelength on the optical responsiveness of Ni-doped ZnO nanorod arrays were studied.The structure of Ni-doped ZnO nanorod arrays was characterized by SEM?XRD? PL and XPS.The results show that under the excitation of different light sources,the photoconductivity and dark conductivity of Ni-doped ZnO nanorod array films decrease with the increase of Ni doping concentration,while the photoresponsiveness increases with the increase of Ni doping concentration;the photoconductivity of samples increases with the increase of annealing temperature;the dark conductivity of pure ZnO nanorod array films is generally higher than that of Ni-doped ZnO nanorod array films at the same temperature.This indicates that the doping of Ni can reduce the dark conductance of ZnO nanorod array films.