Simulation of diamond-film field emission microtetrodes

Using the particle-in-cell simulation code MAGIC, a vacuum microelectronics tetrode with a planar emitter has been simulated. The electron beam stream lines have been evaluated, which show that the upper gate focuses the elect ron beam. The current distribution between gate and anode has been calculat ed and the effect of the lower gate voltage and the emitter size on emitted current and gate capture current has been investigated. Simulation results are presented for a single vertical diamond-film field-emission tetrode wi th the anode biased at 300 V and spaced 50 mu m from the cathode. Simulatio n results indicated that the radius of the electron beam at the anode is ab out 20 mu m for a microtriode, but only about 6 mu m for the microtetrode. The results show that gate capture current should not be negligible in most cases, and can be ignored only if the emitter radius is less than half of the gate aperture radius. Then the percentage of gate capture current to em itted current is less than 0.1%. (C) 1999 American Vacuum Society [S0734-21 1X(99)02801-2].