The authors proposed a method to fabricate field emitter arrays with uniform apex diameters in tens of nanometer scale based on the molding technique and apply it to fabricate molybdenum field emitter arrays. Apex diameter equal to 23 +/- 5 nm was observed in a 6x6 tip array by high-resolution scanning electron microscope. They also studied the field-emission characteristics in devices with gate electrodes fabricated on top of the arrays by a self-aligned process. In single-gate devices, emission current of up to 20 mu A per tip with negligible gate leak current was observed. The gate-fabrication process was extended to fabricate double-gated emitters. Further optimization of the fabrication process for higher emission current, together with metallurgical and lithographic methods, is discussed.