Field Electron Emission from Highly Graphitic Diamond Films with Ball-Like Surface Morphologies

Chemical vapor deposited diamond films with ball-like surface morphologies for field electron emission are reported on Mo substrates. A transparent conducting thin film anode (indium-tin oxide film coated on glass substrate) technique was used to determine the locations of field emission sites on the film cathode. The emission site density was obtained by counting damage spots on the film anode by optical microscopy. These damage spots, caused by the impact of emission electrons, corresponded to the emission sites. With the ball-like diamond films, a low turn-on filed of 2.1 V/μm and high current density of 4 mA/cm² from an emitting area of 0.3cm² were obtained. A field enhancement model and injection mechanism have been developed to explain the low turn-on field and high emission current.