A diamond field emitter diode array with subvolt turn-on voltage and high emission current is reported. The diamond field emitter diode array with self-align anode was fabricated using a new self-ali,on technique, "self-align-gate-sharpened molding." The emission current vs anode voltage of the self-align diamond emitter diode shows an extremely low turn-on voltage of 0.7 V, one of the lowest values reported in the field emission literatures. A high emission current of 4 mu A at an anode voltage of less than 5 V can be obtained from a 2 X 2 array of diamond tips. The turn-on voltage is comparable to conventional p-n:junction diode.