Development Of Low Energy Electron Gun

When X-ray photoelectron spectrometer is used to analyze semiconductor or the poor conductivity sample,the sample surface is positively charged.It impacts the analysis accuracy.Therefore,the sample surface should be compensated by electron.Electron gun emitting electron and projecting to the sample surface is an important method of electron compensation,which is widely used in X-ray photoelectron spectroscopy.The energy of electron emitted by traditional electron gun is 1keV or higer.The electron will cause the interaction between electron and sample surface and damage the sample surface.In order to reduce the negative effect produced by traditional electron gun during electron compensation for the sample surface,a low energy electron gun is designed by using the combined method of numerical simulation and experiments.According to requirement of design,first,designing the type,material,shape and heating mode of cathode of electron gun.Second,the initial electron optical system model of electron gun is designed.Using the electron optical analysis software to simulate the model and the simulation result is analyzed to guide to amend the model.The electron optics system of final model is determined by repeatedly simulating and amending the model.Then,the mechanical design and circuit design of the electron gun are carried out.Finally,an experimental device for testing the performance of the electron gun is builted.The relation curve between the electron beam current and filament current,the relation curve between electron beam current and cathode voltage,the relation curve between electron beam current and spatial distribution,the relation curve between electron beam spot diameter and focus electrode voltage,are obtained by experimental tests.Through analyzing the test results,it is known that the low energy electron gun can effectively achieve a series of functions such as emission,energy control and focus.In the case of vacuum degree is 2×10-4 Pa and working distance is 30mm,electron energy can be continuously adjusted from 0 to 500eV and electron beam current is 12.5?A as the electron energy is 300eV and the beam spot diameter can be continuously adjusted from 20 to 30mm.The performance parameters of low energy electron gun are completely satisfied with the electron compensation for semiconductor or the poor conductivity sample as conducting photoelectron spectroscopy in the ultra high vacuum environment.The successful development of low energy electron gun not only enriches the design of the electron gun at home and abroad,but also promotes the research and development of our country in the field of electron emission.