The field emitter structure includes vertical pillar structures to define un-gated transistor structures. This emitter structure provides high dynamic resistance with large saturation currents. The un-gated transistor structure is formed on a conducting substrate made of vertical pillar structures. This substrate is etched to fill the gap between the vertical pillars with a series of dielectric layers. This technology is inherently scalable, so a plurality of vertical un-gated transistor structures may be formed on a conducting substrate, e.g., where the substrate is made of a plurality of vertical pillar structures to define the un-gated transistor structures. In this case, a series of emitter structures are formed on the vertical ungated structures and positioned in a ballasted fashion to provide high dynamic resistance with large saturation currents.