A new volcano-type triode field emitter array has been fabricated on a glass substrate using titanium nitride as the emitter material. It is based on the process development for the formation of uniform emitters over large areas using reactive ion etching and the sputtering method. In this study, the effects of the ratio of volcano emitter size to gate hole size on the emission characteristics were investigated with a fixed emitter-gate distance of 1.0 mu m and compared with computer simulation results using a finite element method. As the ratio of volcano emitter size to gate hole size decreased, especially from a ratio of around 0.5 to 0.4, the anode current significantly increased. This behavior may result from the increase in the maximum electric field on a tip with a decrease in the ratio as is expected from computer simulation.