Photoelectric Properties And Defects Of ZnS And Its Multilayer Films

In this paper,ZnS,Cu/ZnS and ZnS/Cu/ZnS films were prepared by magnetron sputtering combined with annealing,and the films were characterized by XRD,SEM,EDS,XPS,ultraviolet-visible spectrophotometer,Hall effect test and slow positron beam Doppler broadening spectroscopy(DBS).The effects of sulfur pressure and film thickness on the structure,microscopic defects and optoelectronic properties of thin film samples were studied.For ZnS films,it was found that the sputtered ZnS films had a cubic phase structure.The growth mechanism during the vulcanization process is as follows: the adsorption sulfur internal diffusion on the surface of the film occupies the sulfur vacancy in the ZnS grains,and the grain fusion regrowth occurs in the sulfur vapor atmosphere,and the increase of sulfur pressure promotes this growth.DBS directly confirmed that sulfur vapor annealing can reduce the vacancy defect concentration of ZnS film and improve sulfur deficiency in the film.However,excessive sulfur may cause other defects such as sulfur gap atoms inside the film,and even a small amount of sulfur element is deposited on the surface of the film,affecting the performance of the film.For the Cu/ZnS film,it was found that with the increase of Cu film thickness,the absorption edge of the double-layer film was redshifted and the band gap decreased.At the same time,when the thickness of the Cu film is thin,the porosity of the double-layer film increases after annealing.The empirical formula of positron incidence depth is compared with the SEM results and shows that the actual film thickness results are well in line with the calculation,and through the calculation,we obtain the thickness information of the outer and inner films.DBS results also proved that the increase of copper film thickness can effectively inhibit the loss of S element in the annealing process.The delamination of Cu/ZnS films is obvious,and the defect types of inner film and outer film are different.ZnS/Cu/ZnS films were prepared by magnetron sputtering.The results show that the conductivity of the multilayer film increases with the increase of the thickness of the metal layer,and it has good light transmittance in the visible light region within a certain range.The DBS results show that with the increase of Cu amount,the internal defect concentration of the film increases.The reason for this may be the fact that with the increase of Cu amount,a small number of S atoms in the ZnS film combine with Cu,resulting in an increase in the S vacancy inside the film,and at the same time,some Cu atoms become interstitial atoms,resulting in an increase in the defect concentration of the film.The defect concentration of the film decreases first and then increases with the increase of the incidence depth,and the Cu film is denser than that of the ZnS film.The S-W curve proves that the type of defects inside the film becomes complex as the thickness of the Cu increases.