Research On Fabrication And Performance Of Current Stabilization Of Field Emission Array Cathode

Field emission array cathodes(FEA),with advantages of low working-temperature and power consumption,fast start-up speed high current density and long lifetime,has been widely used in the civilian field and military industry,such as microscopy technology,lighting technology,sensor technology and display technology,etc.What's more,Spindt FEA has always attracted attention most among kinds of cathodes.As for the each emitting unit of FEA alone,it is required increasing the electric field strength on the surface under a lower external electric field,and ensuring the stability of the emission current.However,it is difficult to ensure the uniformity of each emitter unit.For example,the shape of the emission cone and the geometry of the grid hole size are difficult to control.In addition,the surface contamination of FEA,such as adsorbed gas,will also cause the electric field intensity on the surface of each emitting unit to be inconsistent,causing ignition and even damage.The object of this thesis is the molybdenum tip cone of Spindt FEA(Mo-FEA).The silver doped silicon oxide(Ag-SiO₂)film is added between the silicon substrate and the Mo emitter to promote stability of the emission current of the cathode.Working principle is:when the emission current of single emitter unit is overloaded,the resistive characteristics of the silver-doped silicon oxide film are used to realize the transition from the low-resistance state to the high-resistance state.As a result,the voltage of the resistive is much higher than the molybdenum tip,which will force the molybdenum tip to reduce,even close the field emission behavior.In order to prepare the better Ag-SiO₂ film,this thesis studied the influence of SiO₂film thickness,annealing temperature and annealing time on the resistive performance and obtained the following conclusions:1)The thickness of the SiO₂ film has the greatest impact on the resistive performance.When the thickness is between 220nm-520nm,there is a good resistive switching effect.When the thickness of the film exceeds 620nm,resistive switching characteristics disappear;2)When the annealing temperature of the SiO₂ film is 400,500 and 600°,respectively,as the annealing temperature increases,the resistance state changes and the corresponding voltage value extends to both ends.3)When the annealing time is among 3h,4h and 5h respectively,it has little effect on the resistive effect of the SiO₂film.4)This thesis successfully prepared Mo-FEA with Ag-SiO₂ resistive layer and tested its emission performance.The results show that when the anode voltage is 700V and the gate voltage is 102V,the anode receiving current density can reach 0.035A/cm² and the cathode stability is also well.After operating for 7 hours,the cathode emission current is stable at 1m A,and the fluctuation does not exceed 10%.