Field Emission Devices Study Of Secondary Electron Emission

As the research of Vacuum Nanoelectronics (VNE) is attracting more attention, many progresses have taken place in the field of field emission devices (FED). In the process of field emission, the secondary electron emission is inevitable. The secondary emission may induce charge accumulation, change electric field distribution and produce ions which may cause the damage to the cathode through ion bombardment. In this dissertation, the mechanism of field emission and secondary emission are both introduced. Basing on previous researches, we set up a model to simulate the field emission process. Using the Monte Carlo method and considering the space charging effect, we simulate the production and the transmission of the secondary electrons in FEDs, and the collision among particles.We discuss the effect of charge accumulation in field emission devices with four different types of chunnels. Numerical results suggest that in field emission operation, different parts of a chunnel are charged differently. We find that the increasing slope of the chunnel's wall may reduce charge accumulations on the chunnel's underside wall. Also it is suggested that the increase of the chunnel's slope will reduce the ratio of number of primary electrons reaching the anode to that of all electrons reaching the anode.The ion bombardment in a FED equipped with hop and flu spacers has been investigated. We compare the damages of the cathode due to ion bombardment in three different situations. Increasing the voltages on the electrodes will cause more damages to the cathode. In addition, under the same initial conditions, the damage of the cathode in the hop spacer structure is less than that in the normal gate structure.An experimental instrument is set up to observe the energy distribution of electrons (mainly secondary electrons) on the anode screen in the field emission. Simultaneously, the relevant simulation with different initial conditions has been made. Comparing the results of the experiment and the simulation, we found that (1) The simulation results have some similarities with the experimental results; (2) The position of the emitting center has a dramatic influence to the number of electrons that can go out of the hop funnel; (3) The trends of transverse energy distribution in the experiment and in the simulation are similar.