In this work, a high density of spherical polycrystalline diamond field emitter arrays (SPD-FEAs) were fabricated, using microwave plasma chemical vapor deposition (MPCVD) method. Results obtained from the current-voltage (I-e-V-a) characteristics indicate that the impurities heavily influence electron emission. In addition, the emissions current of the phosphorus-doped SDP-FEAs appears to be 25 times lar er than the boron-doped and 120 times larger than the undoped SPD-FEAs.