Cone-shaped metal-insulator-semiconductor cathode for vacuum microelectronics

A cone-shaped metal-insulator-semiconductor (MIS) cathode, in which a field emitter is combined with a MIS structure, has been proposed in order to achieve a low-voltage operation and stable cathode for vacuum microelectronics. The cathode can supply the electrons with higher energies than those at the Fermi level of the metal surface of the emission area, by which the emission voltage and stability of a field emitter will be improved. We made a theoretical investigation on the influence of the electron energy to the electron transmission coefficient. It was found that the transmission coefficient increased drastically with the electron energy. The cone-shaped MIS cathodes were fabricated and their characteristics were investigated in a high vacuum condition. The emission efficiency reached 8% without applying an external electric field. We also confirmed the reduction of the emission voltage by 5 V with the external field. Fundamental characteristics of the cone-shaped MIS cathode have been demonstrated. (C) 1996 American Vacuum Society.