Preparation And Performance Research Of Carbon Nanotube Field Emission Cathode

Carbon nanotubes(CNTs)have attracted the attention of scientists all over the world since their introduction.It has many unique properties,such as one-dimensional nanostructure,excellent electrical,chemical and mechanical properties.Due to its low opening electric field and high emission current density,the cold cathode with CNTs as emitter shows a good application prospect in field emission field.This thesis focuses on the preparation process of CNTs field emission cathode,the post-treatment technology of cathode film and the electron emission performance.Paper creatively and put forward a kind of has a strong adhesive composite CNTs paste,effectively solved by using organic CNTs paste preparation of CNTs film on substrate adhesion is poor and in the test process of flint,fall off,short circuit problem,effectively improve the field emission stability of CNTs films,prolong the service life of the CNTs field emission cathode.This paper has completed the following contents:1.Aiming at the problem of poor stability of organic CNTs slurry in actual field emission,a compound CNTs slurry with strong adhesion was proposed to optimize the slurry.Scanning electron microscope(SEM)morphology characterization and field emission performance tests were carried out to analyze and compare the field emission properties of the two kinds of pastes.It is concluded that the composite CNTs paste has stronger adhesion to the conductive glass substrate and the field emission of CNTs is more stable.2.The effects of screen printing and rotary coating in preparing carbon nanotube films were analyzed and compared.Based on the characteristics of slurry,it is concluded that the rotary coating method is the best technology for preparing CNTs films in the experimental process.Further through a large number of experiments to explore based on the compound slurry spin coating method of the best process parameters,that is,low speed spin coating speed and time is 1000r/min,30s;High speed spinning speed and time of 1800r/min,30s.The high temperature heat treatment temperature and time are 380?,2h respectively.3.Reactive ion etching(RIE)was used to post-treat the prepared CNTs films to remove residual inorganic substances on the CNTs surface.The effects of etching gas,etching power and etching time on the surface morphology and field emission properties of the cathode were studied.It is concluded that CH₄:O₂=50sccm:5sccm as RIE gas,the etching power is 70W and the etching time is 30min,which can effectively remove the sodium silicate on the surface of CNTs film,expose more CNTs and enhance the field emission performance.Finally,the opening electric field intensity of the cathode is3.05V/?m,and the field emission current density is 6.42m A/cm² when the electric field intensity is 5.25V/?m.