Role of dielectric for field emission at the metal-dielectric-vacuum triple junction

In this paper the field emission enhancement at the dielectric-metal contact is theoretically investigated. Even though such a strange phenomenon as vacuum breakdown has been reported for half a century, it is not understood well. However, it has been considered to result from the enhancement of the electric field near the metal-dielectric-vacuum triple junction. Recently it has been argued that the field enhancement is due to the combined effect of the surface charge of metal and the polarization of dielectric. The two opposite charge densities causes each other to become a saturation value. Then the field intensity near the triple junction can be stronger than that in the absence of dielectric.