Preparation Of Single Crystal ZnS Film And Study Of Optical Properties After Nitrogen Ion Implantation

Zinc sulfide(ZnS),as an important wide-band semiconductor material,has great economic value in thin film transistors,photodetector,solar cells and other application fields because of its excellent photoelectric properties,which attracts the research interest of researchers.It is found that the surface morphology and crystallization quality of thin film materials have an important influence on their physicochemical properties,so it is crucial to improve the preparation process conditions and obtain high quality thin film materials for the study of their physicochemical properties.In this paper,ZnS films were prepared by pulsed laser deposition technique(PLD)on Si tablets,and the effects of different annealing temperatures on the crystallization properties of ZnS films were studied.Then,the nitrogen ion doping treatment of ZnS films was carried out by ion implantation technology,and the structural morphology and changes of optical properties of the ZnS:N thin films were studied.The specific research contents are as follows:(1)The ZnS ceramic target with purity of 99.99% was used as the deposition source,and a target laser was ablated by the Nd:YAG solid-state laser PLD.The zinc sulfide films were deposited on the substrate of monocrystalline silicon wafer,and then annealed under the condition of in situ to study the effect of annealing temperature on the crystallization properties of the film.X-ray diffraction analysis showed that the prepared ZnS film was sphalerite type,and the crystallization quality of the film was poor when it was not annealed,and the surface roughness of the film was large.After annealing,it was found that the grain size of the film increased with the increase of annealing temperature,and the surface roughness of the film decreases gradually with the increase of annealing temperature,and the crystallization quality of ZnS film is improved obviously by annealing treatment.By this process,we have prepared the Sphalerite type ZnS film which grows in the direction of(111).(2)Study on doping modification of nitrogen ions: The prepared single crystal ZnS films were doped by nitrogen ion implantation.The results of X-ray diffraction test show that the ZnS films are still sphalerite structure and prederentially growsalong(111)Crystal plane after nitrogen ion doping implantation,but the grain size increases,which is related to the impurity ion nitrogen.SEM and AFM analysis showed that with the increase of nitrogen ion implantation energy,the surface roughness of the film also increased.Mainly nitrogen ions in high energy injection film,the damage to the film is more serious,resulting in increased surface roughness.Ultraviolet-visible spectroscopy analysis showed that after the injection of nitrogen ions,the light absorption limit of the films were blue-shifted and the band gap was increased.Fluorescence spectroscopy showed that the photoluminescence intensity of ZnS films in 420 nm and 440 nm increased significantly after nitrogen ion doping,so that ZnS:N materials could be used as luminescent devices.