Details are given of an experimental study of microfabrication and characterization of a diode electron source using amorphous diamond (a-D) thin films. (100) n-type etched Si wafers with microscale-rough surface were used as cathode substrates. Filtered cathodic vacuum arc deposition technique was employed to coat a thin layer of a-D film on the Si substrate. Using the conventional photolithography, an array of well-defined diode structures with 20 mm gate diameter were formed. In addition, x-ray energy dispersive spectroscopy and atomic force microscopy were used to characterize the diode structure. Furthermore, the total emission current versus applied gate voltage of the diode electron source was measured. The physics of the emission process from the a-D diode was discussed.