Studies on triple junction electric field in ferroelectric cathodes

Abstract

To investigate the effect of grid thickness and dielectric constant on the ferroelectric cathode triple junction electric field distribution in a two-dimensional structure, simulation has been carried out using finite element method (FEM) code ANSYS. Triple junction electric field plays a major role in the emission of electrons from a ferroelectric cathode and it approaches towards its limiting value even if the dielectric constant of the ferroelectric material is increased considerably. It is important to increase the triple junction electric field without increasing the applied field to reduce the mechanical stresses in the ferroelectric material. A dielectric layer (ε_r<100) has been introduced between the ferroelectric material and the grid to increase the triple junction electric field. FEM simulation results showed that the triple junction electric field is more than 48 times the applied field in this case. This structure not only enhances the triple junction electric field but it also changes the E_|| and E_┴ ratio (β) favorably. Effects of dielectric constant and the thickness of the dielectric layer on triple junction electric field have been studied.