The effects of bonding materials in screen-printing paste on field-emission properties were investigated with respect to high-efficient carbon nanotube (CNT) cathodes. The materials used to bond the CNTs to the cathode were composed of an insulating glass frit and a conducting Ag paste. The dependence of the electrical conductivity of the CNT paste, bonding material, and CNT ink on the field-enhancement factor was investigated using the Fowler-Nordheim equation. The emission current from the CNT cathode as the result of an electron tunneling effect was increased with increasing ratio of the dielectric glass-frit fraction in the CNT paste. The larger emission current of CNT cathode containing insulating-bonding materials can be attributed to a combination of the increased effective height of the CNTs, which protrude over the film in the cathode, and an increased field-enhancement factor. (c) 2005 American Vacuum Society.