Triode field emitters with planar-carbon-nanopaticle (CNP) cathodes were successfully fabricated using the conventional photolithography and the hot-filament chemical vapor deposition. Micro-Raman spectroscopy revealed that CNP cathodes, which had been deposited through tiny gate holes, consisted of good-quality graphitic carbons. Electron emission from a CNP triode emitter with a 12-mum-diam gate hole started at the gate voltage of 45 V, and the anode current reached the level of similar to 120 nA at the gate voltage of 60 V, respectively. For the quantitative analysis of the Fowler-Nordheim (FN) type emission from a CNP triode emitter, we carried out two-dimensional numerical calculation of electrostatic potential using the finite element method. As it turned out, a radial variation of electric field was very important to account for the emission from a planar emitting layer. By assuming the graphitic work function of 5 eV for CNPs, we were able to extract a consistent set of FN parameters, together with the radial position of emitting sites. (C) 2003 American Vacuum Society.