Emission stability analysis of cone-shaped metal-insulator-semiconductor cathode by Monte Carlo simulation

We have proposed a cone-shaped metal-insulator-semiconductor cathode (COSMISC) at IVMC’95. The COSMISC emits the electrons with higher energy than the Fermi level of the metal electrode, it is expected that the current puctuation due to the change in work function of upper metal electrode is less significant than a conventional field emitter. In this paper, we analyzed the emission characteristics of the COSMISC in detail with Monte Carlo simulation, especially from the viewpoint of the emission stability against the change in work function of the upper metal electrode. The calculation procedure is as follows: Electrons are generated in accordance with their energy distribution at the semiconductorinsulator surface, and the scattering processes in the insulator and in the upper metal electrode were simulated with random numbers. Emission of electrons into vacuum was judged also in accordance with the transmission probability at the surface barrier of the upper metal electrode. The obtained results are arranged with respect to the work functaon of upper metal electrode and also with resepct to the external field at the apex of the upper metal electrode. It was shown that the change in the emission current of COSMISC with the change in work function 2s lower than that of the conventional field emztter. The change in the emission current of COSMISC with, the change in the external field is also lower than that of the conventional field emitter. The eflect of acceleration of the electrons prior to the ejection to vacuum on the emission stability has been demonstrated.