| Owing to the small grain size and high conductivity of ultra-nano diamond(UNCD),it has great application potential in the field of cold cathode field emission devices.Ion implantation is a surface modification technology that effectively improves the conductivity of diamond films.After annealing,the electrical properties of diamond films can be further improved.In this paper,the preparation of ultra-nano diamond films under different atmospheres was carried out,and the field emission performance changes of the films were analyzed under different atmospheres and after Ni ion implantation of 100keV and 1.0×1017ions/cm2.Secondly,using different annealing methods and annealing temperatures for annealing treatment,exploring the best process that can enhance the UNCD films.The formation of a large number of sp2 carbon bond structures on the surface of the UNCD film and the precipitation of Ni nanoparticles(Ni NPs)provide an effective path for electron release.In addition,the appearance of graphene enhances the local electric field of field emission,resulting in enhanced electron release capabilities.In this paper,scanning electron microscope,atomic force microscope,Fourier infrared spectroscopy,X-ray photoelectron spectroscopy,X-ray diffractometer and Raman spectrometer were used to characterize the microstructure of films,and the Hall effect and high vacuum field emission tests were used to carry out films.Characterization of films'electrical properties to systematically study the key factors that lead to the changes in the microstructure and field emission performance of the UNCD film.The main findings are as follows:(1)Use different atmospheres to prepare UNCD films and explore the effects of different atmospheres and Ni ion implantation on the field emission performance of UNCD films.The results show that the UNCD film prepared in an environment containing N2 has a smaller grain size,a higher proportion of grain boundaries,a higher degree of graphitization,and better field emission performance than the UNCD film prepared in a non-N2 environment.Secondly,after Ni ion implantation,the"pine forest" structure on the surface of the UNCD film prepared in an atmosphere of no N2 and a network structure on the surface of the UNCD film prepared in an atmosphere of N2 are formed.The formation of the shape structure is an important reason for the field emission performance of UNCD films.The formation of two new morphologies provides an effective electron release.The transportation path enhances the electron release capability and optimizes the field emission performance.But the results confirmed that the formation of this network structure is more conducive to the release of electrons.(2)The non-N2 doped UNCD film after Ni ion implantation was subjected to common annealing treatment(CTA)with a temperature span of 400?-900? and a temperature span of 100? in Ar/H2 atmosphere and the temperature was kept for 30 minutes.The effects of different annealing temperatures on the microstructure and electrical properties of UNCD films are discussed.The study found that Ni NPs precipitated on the surface of the film after annealing.As the annealing temperature rises,the precipitated Ni NPs agglomerates and gradually catalyzes the diamond.When the temperature reaches 700?,small flakes of graphene are formed on the surface of the film,and the degree of graphitization is the strongest.This structure provides an effective path for electron migration,making the film conductivity optimal.That is to say,the turn-on electric field is reduced to the minimum(E0=3.09 V/?m),and the current density of 349.66 ?A/cm2 is obtained under the electric field intensity of 4.00 V/?m,and the film resistivity is reduced to the lowest 4.37 ?/sq,and has the highest load.Current concentration(1.719×1026 cm-3)and Hall mobility(161.54 Cm2V-1s-1).When the annealing temperature is too high,a porous structure on the surface of the film is produced,which causes the electron transport path to be blocked and the electrical properties to decrease.(3)The non-N2 doped UNCD film after Ni ion implantation was subjected to rapid annealing treatment(RTA)with a temperature span of 400?-900? and a temperature span of 100? in Ar/H2 atmosphere and the temperature was kept for 30 minutes.The results show that the fast-processed thin film samples have better field emission performance than the ordinary annealed thin film samples.The film annealed at 700?,Ni ions have the best catalytic effect on the UNCD film,resulting in a large number of lamellar graphene structures on the surface of the UNCD film,and the electrons of these graphene sheets are very active,and it is easier to use a lower extra Energy is emitted from the surface.In addition,a certain localized electric field is generated at the edge of the graphene,which effectively improves the field emission performance of the UNCD film.The turn-on electric field is only 2.72 V/?m,and a pole of 441.93 ?A/cm2 is obtained at an electric field strength of 4.68 V/?m,and the film resistivity is reduced to the lowest 4.37 ?/sq,and has the highest load.Current concentration(1.719×1026 cm-3)and Hall mobility(161.54 cm2V-1s-1).High current density.When the rapid annealing temperature continues to rise,the selective catalysis of Ni ions leads to the disappearance of the sheet-like graphene structure on the surface of the film,and the formation of a large number of porous graphene structures causes the field emission performance to decrease. |
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