Research On The Technology Of Field Emission Array Steady-current PN Junction Based On Diffusion Method

Compared with the traditional vacuum cathode,the field emission array cathode has many advantages attributing to its work principle,such as cold cathode,high current density,low voltage modulation,anti-radiation and instantaneous start.However,it is difficult to ensure that each field emission unit has the capability of same emission due to the difficulties in manufacturing process.As a consequence,the current density of the field emission cathode is not uniform and some is too high to have a large current load and easy to be wrecked,leading to the vacuum discharge and making the whole cathode wrecked,which greatly reduces the life cycle of the cathode.In this paper,a PN junction steady-current structure of the field emission array based on the diffusion method has been designed,in order to protect the field emission device,enhance the field emission performance and extend the life of the device.Moreover,the paper analyzes the process parameters that have significant influence on the characteristics of current steady.It mainly includes four aspects as follows.1.The research,design and simulation of PN junction steady-current structure.Taking PN junction reverse characteristic into account,the steady-current structure of the FEA cathode was designed.By the calculation of the reverse current density,the paper determines the factors and parameters required for the structure.What's more,the paper simulated the diffusing parameters and got the relationship among the diffusion process,the electrical characteristics of the PN junction and the reverse I-V characteristic curve which can guide the experiment.2.The research and testing of PN junction steady-current structure preparing process.In this paper,the impact of the diffusion temperature,the diffusion time and the gas flow rate on the performance of the PN junction prepared by diffusion method had been studied.The analysis showed that all four factors had a significant effect on the doping process and doping uniformity of the silicon substrate,and the amount of doping would affect the reverse I-V characteristic curve.What's more,the experimental results were consistent with the simulation results,which determine the parameters.3.Spindt Field Emission Array cathode fabrication and field emission performance test.Preparing molybdenum field emission array cathode by electron beam evaporation coating,this paper studied the effect of the key processes such as the process of cavity preparation,sacrificial layer and electron beam evaporation on the Cathodic Morphology of Field Emission Array.Meanwhile,the paper also analyzed the Cathodic Morphology of Field Emission Array and tested the field emission performance of the array cathode.In conclusion,the emission current density of the cathode prepared by electron beam evaporation was 0.75 A / cm~2 with the duty Ratio ~ 30%,and the voltage ~ 97 V.